Works good for me. I'm pursuing my private pilots license and recently I used "My Tracks" app on a flight. Stuck the phone on the floor behind my seat, hit record and I was able to see my entire flight from wheels up to parking it.
It was pretty cool to see my maneuvers on google maps.
I've started biking to work (both to lose weight and save money). It's a 25 mile bike ride, and I use "My Tracks" to keep up with my stats during my ride (speed, etc...). love that app.
You can upload your stats to Google Docs and track your progress from day to day.