Apple Watch Series 8 review: Still the winning formula

Apple predictably dropped the Apple Watch Series 8 at its event in Cupertino – as it’s done every year since the first-gen model launched in 2014.

We’ve greedily feasted on every fresh iteration, but this year is different. Apple chose to launch the new Apple Watch Ultra, with bags of new tech and a rugged new look, and replace the absurdly dated Series 3 with a moderately revamped SE 2.

So, what of the Series 8? After a new look in 2021 and a packed watchOS 9 (for Series 4 and newer), the Series 8 is one of the most minor upgrades in Apple Watch history.

> watchOS 10: All the new features coming to Apple Watch

In many ways, the Series 8 has taken a year off, letting the Ultra grab the spotlight, before presumably returning with a bang in 2023.

This means there are very few reasons for anyone to fork out to upgrade from the Series 7. It retains the 41mm / 45mm case and larger display of the previous model - meaning there is zero difference visually between the two generations.

All that said, the Series 8 is still the best smartwatch money can buy. Apple could likely release the same watch from now until 2025 and still be ahead of its competitors.

Here’s what’s new – and what Apple still needs to achieve:

> Best smartwatch – read our top review picks

New temperature sensor

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There is one major improvement on the Series 8, and it’s a big one for 50% of the population.

The Series 8 debuts a temperature sensor (two, to be precise), and it’s being used to leverage advanced cycle tracking for women.

The Apple Watch has had cycle tracking since Series 5, but, like most wearables, it simply involved logging symptoms in a calendar.

Compared: Apple Watch Series 8 vs Watch Ultra

The Series 8 offers ovulation tracking via skin temperature changes, but it will also look for shifts in your cycle, which can be linked to certain conditions.

Ovulation detection is retrospective and will inform you what happened last week, and the old-style calendar logging will still offer cycle predictions going forward.

Our testing of this feature is underway, and we’ll be publishing a deep dive into how it works – and its effectiveness. Naturally, it will take a few months to draw conclusions.

For those with concerns about privacy after Roe v Wade, it’s opt-in and end-to-end encrypted, so not even Apple has the key to your data.

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Anyone can see temperature data on their Apple Health app.

The feature works by spending five nights finding your baseline temperature – after which a nightly average will be taken and shown against your personal temperature baseline.

You won't see an absolute temperature. It's displayed as a temperature difference from your baseline, which isn't disclosed. It doesn't really make sense to show an absolute skin temperature reading, as it's personal to everyone. The key takeaway is whether this number changes.

Elevated temperature can show your cycle has started, but it can also be a sign of illness or alcohol consumption, so you don’t have to be a woman to find it useful.

In our testing, things were pretty steady, with a slight spike on a night when we drank alcohol. Spikes correlated with Whoop 4.0, although the two had clearly established different baselines. Again, that's fine, because it's the deviations that matter, not the absolute numbers.

Still, like so much of the Apple Watch health tracking experience, if you want to use temperature data for non-cycle tracking of wellness, you'll have to make sense of the data yourself.

Health tracking and presentation

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Finding temperature data – or any core health stat from heart rate, resting HR, HRV, and step data – means a trip to the Apple Health app.

It's a mindbogglingly complete app – and there’s nothing out there that can provide such an intense dose of health data. Especially as it can aggregate data from any other wearables you have.

You can set up the home page to show whichever metrics interest you – and there’s stuff we didn’t even know we needed, like heart rate recovery after workouts and bedtime regularity. The focus on trends is also pretty helpful, and you can track most data points over a year.

Our only criticism is a lack of actionable takeaways from each set of data.

Apps such as Whoop highlight and color code problematic biometric data – and Fitbit will also show when key metrics have moved outside of your baseline.

But, while Apple Health tracks a bonkers amount of biometric data, most of it is presented without comment. A massive spike in resting heart rate? Body temperature spike? Unless you notice and draw conclusions, Apple Health doesn't make any sense of the data for you.

New safety features

However, Apple does go big on safety features - and when it does deem information worthy of alerting you, it's hard to miss.

You’re most likely to run into a high/low heart rate notification, and we sometimes got a warning of low HR during sleep.

Then there are environmental noise alerts, Fall Detection, and, new to Series 8, car crash detection. This is leveraged from improved accelerometer and gyroscope sensors – and will call emergency services if it detects a car crash.

Thankfully, it’s not one we had cause to test – and we’d say it’s not a feature that will make us part with our cash. But it’s another part of a growing list, with ECG and continuous Afib detection, which begs the question, can you afford not to?

Battery life woes

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watchOS 9 has introduced Low Power Mode – which we’ve fully explained after chatting with Apple representatives.

It ups battery life from 18 hours to 36 hours on paper, though we found it could extend over two days from our testing (we got around 80 hours from a full charge in Full Power mode).

That will keep your Series 8 going for a weekend away, although there are significant sacrifices. And these sacrifices - always on display, heart rate and notifications - are such that most people won’t want to do that, we think.

Ultimately, the fact remains that the Apple Watch battery life hasn’t changed in eight years. In our experience, it was good for around 25-30 hours, including a workout and a night of sleep tracking.

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In the old days, the Apple Watch was charged overnight and then worn during the day. It was a simple routine. Now with sleep tracking, things are trickier.

Putting a charger on our desk helped day-to-day. But, when away for the weekend – with a round of golf to track – charging became a problem to solve.

We ended up walking out of the door without the Series 8 one day, as it needed to be charged while having breakfast, and was left, forgotten, in the hotel room.

People are within their rights to gripe about the battery life. It’s still the Apple Watch’s Achilles heel, and it’s becoming more and more annoying.

Low Power Mode, along with fast charging, which can give you 20% charge in around 10 minutes, does make a difference. But the allure of the Apple Watch Ultra's extra battery shows where the Series 8 needs to go.

watchOS 9 new features

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While the Series 8 is a minor improvement, watchOS 9 brings the best changes.

One major addition is the tracking of sleep stages. Remember, Apple only started tracking sleep in watchOS 7, and now has expanded this data to include stages. That means deep, REM, and wakeful periods.

We’ve always found Apple Watch sleep data to be pretty accurate, matching up to Whoop and Fitbit well.

Without a sleep lab, it’s impossible to validate the accuracy of stages at home, but, generally, we found that specific stages lined up closely with our other trackeers.

That gives a lot of reassurance that what’s being tracked is real.

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The key difference between Whoop and Apple Watch was how much wakeful time was registered per night. Whoop often deemed us more restless – and tended to judge our rest more harshly.

But, overall, there’s good reason to trust the Apple Watch – and we like the onus it puts on bedtime consistency and sleep duration, which is more actionable than stressing about how many minutes of REM sleep you clocked up.

There have also been improvements to the Calendar app and the way notifications are handled on the watch. The Compass app has had a massive overhaul, too, with some actually useful features, such as auto-marking the location of your car and navigating to waypoints.

However, watchOS 9 turns the Apple Watch into a fitness powerhouse – and that’s still unmatched by any other consumer smartwatch.

Brilliant sports tracking

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In eight generations of the Apple Watch, there’s no doubt it has developed into an incredible sports watch.

watchOS 9 has brought a new bunch of additions that improve on that further – including advanced running metrics, such as running power and vertical oscillation, that will certainly have the likes of Garmin and Polar sweating.

The workout app is bustling with different profiles, with excellent running, swimming, and cycling tracking.

And if there’s an activity that you particularly like, you can browse the App Store for dedicated experiences.

Post-run workout analysis has improved dramatically, and a head-to-head with a Garmin Fenix 7 (with HRM-Pro) produced similar data for vertical oscillation and cadence.

Heart rate performance continues to be excellent, as well, as we’ve found across most generations of the Apple Watch – with a 50-minute run producing data around 2bpm shy of a Garmin chest strap.

Jumping about, doing HIIT and things like CrossFit will produce increasingly divergent results – such is the limit of optical sensors.

Running power is an interesting metric, although on Polar devices it's a live readout, to help you pace races.

On the Apple Watch, running power is only produced after the workout, and despite being experienced runners, isn’t wasn’t clear how to use the reading, beyond comparing effort levels on runs.

Should you buy the Series 8?

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If you’re a Series 7 owner, there’s very little reason to upgrade – unless you’re a woman that wants the cycle tracking capabilities. However, we’re waiting for our specific testing to finish before we make any recommendations there.

For first-time users or owners of older generations of Apple Watch, the Series 8 is still the pinnacle of the range, and the easiest to recommend, even in the age of the Apple Watch Ultra. Go buy it with our blessing.

However, now is a great time to snap up a Series 7. We’ve seen deals that save nearly $100/£100 on the price of Series 8.

Don't forget about the Apple Watch SE, either, as this is another superb choice for first-time users and those who don't mind missing out on the design and advanced features of the Series 8.