Just tap. That's it!
I have a medical condition that requires me to take my heart rate several times a day, so I tried a lot of different apps, but none of them can compare to this app.
It's super easy to use--you don't have to do anything but tap, and it will take and log your heart rate. I had been logging manually into an excel spreadsheet before, but now I'm done after tapping.
It's also great how you don't have to decide if you want it to count 10 or 6 seconds or heartbeats. The app does it all for you, getting the most accurate heart rate out of any apps I've tried.
Editing and deleting if you mess up or let someone else try it is also easy, since it's the same as the rest of the iPhone (swipe to delete, etc).
It's pretty, functional, and easy to use. Definitely worth buying!