While I wasn’t originally looking for a separate Heart Rate app, HeartWatch had excellent reviews and looked like it would appeal to a stats geek like me.
I’m super-impressed with it. I actually use it over the the included Apple Exercise app because I like capturing my HR recovery explicitly after a workout.
There is no shortage of stats you can review: Average and Maximum heartrate while exercising, (separately) while sedentary, and while sleeping.
I especially like the history calendar where you can look at nearly 2 months worth of each stat individually and see how things are changing over time.
I’m very pleased with this quasi-impulse purchase!