Apple Watch Series 12 Review: Live Rewind Needs an iPhone 16

The watch itself pairs with an iPhone 11 or later, including the second-generation iPhone SE, running iOS 27. The features that explain its new microphone ask for much more. According to Apple's specification footnotes, Live Rewind and Siri Recap need an Apple Intelligence iPhone 16 or later, excluding the iPhone 16e, arrive as a beta in late 2026, start in English and will not be available in the EU at first. Sound Recognition and the faster Shazam are the parts of Audio Intelligence that do not carry the iPhone 16 condition.

Live Rewind shows a transcript of the last 15 seconds around you when you press the Digital Crown twice. Tom's Guide reports that it plays a chime even when the watch is on silent and shows a microphone indicator on screen, and Macworld adds that the sound cannot be turned off. California's governor vetoed a bill that would have made such indicators mandatory on wearable recorders, as covered in the SB 1130 veto, so Apple's chime is its own design choice.

Apple says server-based Apple Intelligence features, Live Rewind and Siri Recap among them, are subject to daily usage limits, and that expanded access will be available for a fee in the future, without saying what that fee will be.

Apple rebuilt the sensor on the back, and the heart rate complication now updates every five seconds, 60 times as often as on the Series 11, according to Tom's Guide. The Heart Rate app shows a rolling two-minute chart, and HRV, including overnight and recovery readings, is easier to reach from the wrist. Its reviewer ran with a Garmin chest strap for comparison and found the watch close to the strap on the runs shown.

The new Readiness score, a rating out of ten with one of four recommendations, is exclusive to the Series 12 and Ultra 4. It needs seven nights of wear with at least four hours of sleep before it appears, and the Readiness tab in the iPhone's Health app arrives with iOS 27.2, Macworld notes.

Hypertension notifications are listed on the spec sheet, but Apple excludes people under 22, anyone already diagnosed with hypertension and pregnant people, and the feature is still waiting for clearance in many regions, as covered in the regional rollout of hypertension alerts. The Blood Oxygen app remains a wellness feature, not a medical one, by Apple's own wording.

Apple's 24-hour rating assumes 300 time checks, 90 notifications, 15 minutes of apps, an hour-long workout with music and six hours of sleep tracking, with the watch connected to an iPhone the whole time. Low Power Mode is rated at 38 hours, and a GPS workout at up to 10 hours, two more than the Series 11 by Tom's Guide's count.

Macworld's two cycles lasted 51 hours and about 40 hours, an average of 45.5 against 47.5 for its Series 11, and the reviewer called the new watch less consistent. Charging fell short of Apple's claim of 80 percent in about 30 minutes: Macworld reached 58 and 72 percent in that time, and a colleague at Macwelt reached 62. Full charges took 82 and 63 minutes.

In practice that is a charge every night or every other night, depending on how much the screen and workouts are used.

Macworld's watch reset itself three times in one day and sometimes felt slow to respond. Apple has since released watchOS 27.0.1 to fix random reboots on the Series 12 and Ultra 4, Notebookcheck reports, so check that update first if a new watch restarts on its own. Notebookcheck also reported a small number of owners describing skin irritation, and Apple Support advises them to stop wearing the watch, in many cases with a free return.

The body is the Series 11's: 9.7 mm thick, 32.2 grams for the 42 mm aluminum GPS model, water resistant to 50 meters and rated IP6X for dust.

iPhone in Canada's advice is that Series 11 owners can comfortably skip this generation and that the upgrade grows from a Series 8, 9 or older.