It works great for standard tabata and rounds timing provided youre okay with the default settings. You have to buy the full version (2 bucks currently) to change number of rounds or timing from default --8 rounds of 20 sec on 10 sec off for tabata, 15 rounds of 30 sec each for rounds. You also have to buy the full version to change the sound effects and certain other options. The app does run well in background mode and even plays the end-of-round beeps on top of Pandora.