Works very well!
I usually dont rate apps. I wanted to rate this one because I was so impressed. Im using it on an iPhone 5 with the latest OS. Its not optimized for the taller screen, but that doesnt affect functionality. I used this at my last band practice and wasnt expecting it work. I couldnt believe how quickly and accurately it started tracking the bpm, even despite the very loud volume of our music. One thing I noticed is that it sometimes loses the time signature. For example, it might be reading at 120bpm, but then a change in drum pattern will cause it to read at half or double tempo. This happens very rarely and doesnt affect the usefulness of the app. The only change Id like to see in future updates, other than being optimized for iPhone 5 screen, is the ability to tap something to indicate where a song starts and stops. Sort of like a lap timer on a stopwatch. That way I could go back and look at the tempo graph for various songs. All in all, its a great app.
JonLong about
liveBPM - Beat Detector