Editing tracks can be cancelled without confirmation -> everything lost
To me, this is a biggie:
When editing a track (insert/edit trackpoints), it's possible to cancel editing with just one tap in the wrong screen area - and everything done so far is lost!
It happened to me more than once that I edited quite a lot of points at once, wanted to hit "OK", but instead tapped slightly below the OK - poof, everything was gone!
I think it either shouldn't be possible to cancel edit any other way than hitting "Cancel", or there should be a confirmation message ("Do you really want to cancel and lose all edits?").