Early reviews of the Apple Watch Series 12 and Apple Watch Ultra 4 are available ahead of their launch on Friday, September 18, finding largely familiar designs but several internal upgrades.
Both new models share key changes this year: a more powerful S11 chip; larger LEDs on the optical heart sensor that enable more accurate and more frequent heart‑rate sensing; HRV measured up to 24 times more often; a new Readiness app; more accurate step tracking; and faster charging. Two new Audio Intelligence features, Siri Rewind and Live Recap, are slated to arrive later this year as part of an upcoming watchOS update but were not available to reviewers.
Apple Watch Series 12 performance, sensors and battery
Reviewer Victoria Song reported that the S11 chip noticeably speeds up Siri AI, saying “Siri AI queries are faster on the Series 12 than my Ultra 3.” Song also noted that the higher‑frequency heart‑rate sensing did not produce a measurable hit to battery life: “I didn’t notice a negative impact to battery life from continuous heart rate tracking.” She added that the Series 12 keeps the Series 11’s 24‑hour battery estimate and highlighted faster charging as a mitigating factor, reporting a 20‑minute charge that took the watch from 20 to 64 percent.
Readiness app and health tracking
The new Readiness app provides a continuously updating readiness score that adjusts through the day rather than delivering a single morning score. Reviewer Vanessa Hand Orellana noted the score updates as daytime vitals are measured and ranges from 0–10 with advice such as Recover, Pace Yourself, Ready and Go for It. Apple also provides the data behind the Readiness score without an additional subscription. By contrast, Oura shows a Readiness score without a subscription but requires a $7 monthly fee to access deeper metrics and long‑term trends, according to the reviewer. Apple’s readiness score requires “at least” seven nights of data, and several reviewers said they still had not received a score after about a week of testing.
Ultra 4 battery life, unavailable features and other notes
In battery testing, reviewer Chance Miller found the Apple Watch Ultra 4 met Apple’s battery life claims, reporting 48 hours on a single charge in a real‑world test that included 90 minutes of workout tracking, three hours away from the reviewer’s iPhone, and two nights of sleep tracking. Siri Rewind and Live Recap were not available to reviewers at the time of these early impressions.
Reviewer Cherlynn Low called the new models a “solid upgrade,” citing a meaningful overhaul of the health sensing system, expanded gesture support for more hands‑free interactions, a new type of HRV measurement, increased sampling rates and additional watch face complications. New case colors and options include Light Bronze aluminum and the return of ceramic in Pearl White and Night Blue.
Full evaluations will depend on wider testing and on features that arrive later via software updates.
