Apple Watch Series 12 Review: Heart Rate Monitoring Improves, AI Still Not Ready

watchOS 27 brings a handful of light changes, notably to the Liquid Glass design, updated this year to be more discreet. But the most visible interface change is the replacement of the home screen and its galaxy of apps with a simpler new menu. Six apps are highlighted, chosen from what you use most or recently opened.

A smart algorithm manages the selection and arrangement of software. After several weeks of testing through various betas this summer, I found nothing to complain about: the suggested apps are relevant at different times of the day. It’s still possible to access all apps by turning the digital crown. Apple changes our habits, but this time I didn’t want to go back. These changes come with watchOS 27 and benefit older compatible watches as well.

However, one notable absence: Siri AI. The AI-enhanced Siri is still not available on the Apple Watch in the European Union. Apple attributes the delay to the DMA and its disagreements with European authorities for bringing the assistant to iPhone and iPad first.

On the wrist, Siri AI would require a watch paired with a compatible iPhone with the new assistant enabled. Its unavailability on the iPhone in the EU also deprives the watch of it. The standard Siri remains, but for the big rewrite, we’ll have to wait a bit longer.

Another miss: Workout Buddy, the AI-assisted fitness coach. It can now accompany you without the iPhone nearby, provided you have a Wi‑Fi or cellular connection, but it still only speaks English and Spanish. For French encouragement, you’ll need to manage on your own or run with a particularly enthusiastic friend.

Delays and gaps that annoy a little more every year. Between geographic restrictions and languages left out, there is now a two-speed development of AI features at Apple, and we’re on the slower side of the game.

Sport and Health: Apple Has Put Heart into It

Now to the hardware standout of this Series 12: its heart-rate sensor. Apple claims readings every five seconds, all day long. In my usage, the clearest benefit is the steadier tracking, with updates that happen very frequently.

During workouts, there were no dropouts, whereas my previous Apple Watches could lose the thread. How many times during my daily walks did the heart-rate tracking drop out for hundreds of meters? With the Series 12, I didn’t encounter this issue during my two-week test.

The real change is in the back, with the integration of the new heart-rate sensor. The LEDs are larger and their arrangement has been redesigned. A change that you’ll forget quickly once the watch is on, but we expect more than a pretty back panel: more regular readings and, above all, information that serves a purpose.

Display: The Same Pixels, a New Protection

I’ll be brief about this section. The Series 12 preserves the definitions and brightness levels of the Series 11, so I’ll direct you to our full test of last year’s model to revisit our thoughts on the display.

If the technical specifics don’t move you, note that the maximum brightness remains at 2,000 nits. It lags behind Samsung Galaxy Watch 9 or Huawei Watch GT 7 Pro at 3,000 nits peak. These figures don’t alone decide display quality on the wrist, but Apple isn’t chasing the ceiling here either.

Conversely, brightness drops to as low as 1 nit in total darkness to avoid dazzling you when waking up or disturbing a neighbor in the lounge or at the cinema. The always-on mode is of course part of the package.

The novelty sits above the panel: aluminum models adopt Ceramic Shield 2, which Apple claims offers greater durability than the Ion-X glass of previous generations. Titanium and ceramic versions, meanwhile, feature sapphire glass. My complaint remains the bezels, which still look a bit thick around the display.

Performance: The S11 Chip Lets watchOS Sing

Two years in, Apple largely recycles the Series’ System in Package. This time, the Series 12 introduces a new S11 chip, with a 64-bit dual-core processor and a four-core Neural Engine. Storage remains at 64 GB.

Performance has never been a problem for the Apple Watch, even if I noticed a few odd latencies on Series 11 after updating to watchOS 26. Those rare issues are now history in my use of the Series 12, which makes its OS sing like never before.

Animations stay smooth, apps feel quicker, and most notably, loading data is noticeably faster. For instance, opening an email or fetching WhatsApp messages on the wrist happens instantly, where the previous model required a few seconds. Even after multiple days without a reboot, everything remains fluid. It’s hard to separate the improvements from the chip, the watchOS optimizations, and potential app updates, but on the wrist the result is tangible.

The Series 12 also finally maintains 5G compatibility on its cellular versions, provided you have a plan and carrier that supports it. I could only test 4G, but during a trip away from the iPhone, calculating a route in Apple Maps and starting a playlist worked without a hitch.

The Health app on iPhone could bring some answers with its redesign planned for the end of the year. Apple aims for a redesigned interface and analysis features based on Apple Intelligence, but the rollout should begin in American English. For French guidance, you’ll have to wait a bit longer, with no timetable guaranteed at this stage.

As is, this Readiness Level is a step in the right direction, but it remains too lightweight for those who expect detailed guidance from their watch to tailor workouts.

For the rest, the sport-tracking retains its broad array of activities, not counting Apple Fitness+ sessions available by subscription. With watchOS 27, Apple slightly revised the Exercise app interface: you can now start an activity with a tap on its card, without aiming for the small start button.

A detail for you? Perhaps, but a nuisance for many others, including yours truly, who is glad to see that one is now history.

Battery Life: 24 Hours Claimed, Near Two Days in My Experience

Despite the new S11 chip and more frequent heart-rate readings, Apple remains vague about the Series 12’s autonomy, still advertising 24 hours. Yet, I managed nearly two full days between charges, with two nights of sleep tracked, 40 minutes of exercise on 4G, and without strictly limiting notifications.

This result aligns with my use, but it leaves ample room for improvement compared to the manufacturer’s claim. If you forget to charge in the morning before leaving for work, you shouldn’t have to spend the day watching the battery icon.

Charging has also evolved. Apple now promises up to 12 hours of use recovered in 15 minutes, versus 8 hours on the Series 11. For my part, a full charge takes about an hour, with 80% battery in 35 minutes, five minutes more than the company quotes. Not catastrophic: a short break on the charger gets you back on track without disrupting your routine too much.

Apple Watch Series 12: Clubic’s Take