I've used previous versions of Harry's lap timer. Works fairly well. Works even better if you add an external GPS.

Biggest problem is you were limited to phone screen size to analyze results. So, good for recording lap times, and video (my version didn't do that). But dedicated lap timers (like aim solo) have better analysis software (that comes at a price).

I don't know if you could output the harrys lap timer data to another analysis software.