Reviews for the Apple Watch Series 12 and Apple Watch Ultra 4 are out ahead of Friday’s launch, and nearly every outlet is zeroing in on the same redesigned health sensing system, one that now measures heart rate every five seconds instead of every five minutes.
The rest of the story splits along familiar lines. Design is nearly unchanged on both watches, battery life jumps meaningfully on the Apple Watch Ultra 4 but barely moves on the Apple Watch Series 12, and Apple’s upcoming Audio Intelligence features are drawing real privacy pushback before they’ve even shipped. Here’s how each review breaks down.
Tom’s Guide Calls the Apple Watch Series 12 the Best Smartwatch on the Market
Tom’s Guide gave the Apple Watch Series 12 its Editor’s Choice award, calling it the best smartwatch on the market for most people. The reviewer said this is the first year since the original Apple Watch Ultra launched in 2022 that she’d be genuinely torn between the standard and Ultra models.
The redesigned heart rate sensor uses a 32-petal layout, up from two petals on the Apple Watch Series 11, and takes a reading every five seconds instead of every five minutes. Tested against a Garmin chest strap, the reviewer found the readings landed close to spot-on, matching the data Apple published on its own heart rate accuracy claim. The new daily Readiness Score, rated 0 to 10, tells wearers whether to recover, pace themselves, stay ready, or push hard.
Battery life held at 24 hours, the same as the Apple Watch Series 11, though charging sped up to 80 percent in 30 minutes and GPS mode now lasts 10 hours instead of 8. Her complaints were the unchanged battery duration, an identical display and design, and privacy questions around the Siri Recap feature, which can record ambient audio every 15 minutes.
Engadget Scores the Apple Watch Series 12 a 9.1 Out of 10
Engadget gave the Apple Watch Series 12 a 9.1 out of 10, its highest mark in this roundup, crediting a health sensing system with more densely packed diodes, electrodes and LEDs. Background heart rate now reads every five seconds instead of every five minutes, and heart rate variability readings jump from once every two to four hours to as often as every five minutes.
The reviewer pointed to a new single-tap gesture that joins the existing double-tap and wrist-flick controls, calling the added hands-free functionality especially useful for accessibility. She was not able to get a Readiness score by the time her review published, despite wearing the watch for several nights.
On Audio Intelligence, she noted that Live Rewind and Siri Recap, the features that transcribe nearby conversations, were not yet available to test, and that Apple lets users opt out of them entirely without losing other functionality. Her complaints were a dynamic app grid that sometimes buries the app she wants and a Shazam widget that occasionally got stuck on a previously detected song.
9to5Mac Says the Health Sensing Overhaul Is the Biggest Update in Years
9to5Mac’s Chance Miller called the new Health Sensing System one of the biggest updates the Apple Watch line has seen in years, spanning both the Apple Watch Series 12 and Apple Watch Ultra 4. Apple redesigned the electrodes for better skin contact, arranged the photodiodes in a ring pattern, and enlarged the green LEDs, and says the result beat every competing wearable it tested for overall accuracy across more than 1,000 participants.
Battery gains were uneven between the two watches. The Apple Watch Series 12 stayed at 24 hours of normal use, while the Apple Watch Ultra 4 jumped from 42 hours to 50. Design changes were mostly cosmetic, with ceramic finishes in Night Blue and Pearl White returning for the first time since 2019, alongside new Radiant Gold titanium and Dark Bronze and Light Gold aluminum options.
His main criticism was that automatic workout detection hasn’t improved despite the far more frequent heart rate readings. He recommends the upgrade for anyone still on an Apple Watch Series 9 or older, framing this generation as refinement rather than reinvention.
Gizmodo Focuses on the Apple Watch Ultra 4 as a Heart Health Tool
Gizmodo framed the Apple Watch Ultra 4 around its redesigned photoplethysmogram sensor, which now captures heart rate variability data 24 times more often and resting heart rate five times more often than before. The review paired the new sensor with an updated Heart Rate app, a Vitals app, and the same four-tier Readiness score found on the Apple Watch Series 12.
Battery life came in at over two days of normal use, with up to 45 hours available during workout tracking with every sensor running. The Apple Watch Ultra 4 keeps its titanium case and $799 price from the previous generation, with no cosmetic changes beyond the new sensor housing on the back.
The review also covered upcoming Audio Intelligence tools, including Sound Recognition and Live Rewind, without raising concerns about how they collect audio.
DC Rainmaker Questions Apple’s Heart Rate Accuracy Claims
DC Rainmaker’s Ray Maker tested the Apple Watch Ultra 4 across trail runs, road cycling, rowing and track workouts against a Polar H10 chest strap and a Garmin Fenix 9. GPS accuracy came in very close to the Fenix 9 in most conditions, with multiband positioning holding up well on technical trails even after Apple dropped GLONASS support on the new model.
He pushed back on Apple’s accuracy claims, pointing out that the watch discards heart rate readings it isn’t confident in, and that Apple’s own study only compared timestamps where both devices had usable data. That approach, he wrote, skips over exactly the difficult moments where sensors tend to disagree.
“Apple’s study appears to have rules stacked in their favor.”
A two-hour ride used 11 percent of the battery, working out to roughly 19 hours of GPS use, just under Apple’s 20-hour claim. He did hit the advertised two-day battery life in everyday use, and called Instant Shazam reliable, though the sound recognition feature mistook his Nespresso machine for a doorbell more than once.
His verdict was that the Apple Watch Ultra 4 is a solid upgrade for Apple Watch Ultra 1 owners, though we’ve also laid out how much of a jump it is over last year’s Apple Watch Ultra 3 for anyone weighing a more recent upgrade. Apple’s accuracy claims over rival sports watches, he said, aren’t yet backed up by its own testing methodology.
Here are also some select YouTube reviews for the new watch models:
The Apple Watch Series 12 starts at $399 and the Apple Watch Ultra 4 starts at $799, both going on sale September 18. Both have already picked up their first discounts ahead of launch, with the Apple Watch Ultra 4 dropping to $779.99.
