Heart Rate Monitor

[Tartarus]

I'm guessing the watch still uses that same sensors as the original, so I don't expect accuracy to change. What HAS improved is the speed with which the app launches.

During the presentation Apple said that they have improved the sensors and that it would even be more accurate than it already was.

 

[salscott]

Can verify that I find it more accurate during workouts. I can't give great detail because I now have an AFib condition and before that have 7 years of history I could compare during workouts. Typically, they struggle with interval training but s4 seems much improved