In interests of being semi-impartial, here's another review of the KER ClockIt App I reviewed last Friday:
Fitness Trials and Tribulations: Galloping the Warmblood
...though, KER is sponsoring the review, soooooo.
I did note in the original review that perhaps it would work better with an attached heart rate monitor. The author of the EN review did use a heart monitor and seems happier with it.
So if I ever do purchase one, I'll try again for sure. In the meantime, without the heart monitor, the app sucks.