I like the ability to choose from different tones for the beep, and the configurations for how the alarm can be set off.
My only critique is that the beep could sound a little more ominous than it already is.
To elaborate; the alarm begins at a slow pace and picks up to a medium pace. However, I would like for it to step up once more to a rapid pace (ideally double the tempo of the current fastest pace) after more time has elapsed. If the app could do that, it would earn 5 stars from me.