When I downloaded it (about 2 months ago) the only difference between the free and paid versions is that the paid one had more choice of colours and designs to customise the little graphic of the battery. I'm the sort of person who never changes the ringtone on the phone, though, so I don't care.

Apart from that, they're exactly the same software, I think. Works fine, never crashes, timings and battery life estimates seem very accurate to me.

kodokan - just trying to save you a franc or so