I’ve had one for about 8 months now, first proper smartphone, cost about £150 second hand, on GiffGaff PAYG (unlimited data for £10/month).
I like it but I’d say you need to be tinkerer to get the most out of it. If you’re fairly Android savvy and don’t give a stuff about the warranty then it’s a good rugged phone.
Pros: Battery life is reasonable. Good GPS. Relatively cheap. Hard to scratch the screen. Has survived lots of dunkings including 10 minutes in the washing machine.
Cons: The big one is that capacitive screen becomes useless in rain, and annoyingly even a bit of sweat can decrease the functionality. The screen isn’t completely scratch resistant and reports suggets it’s quite brittle. The earpieces of almost all the first gen ones seem to die, it’s a £3 part to replace but shouldn’t need doing. Battery life isn’t enough to use as a GPS except for quick local blats. Laggy processor compared to more expensive, newer phones.
I upgraded to Android 2.2 and it became agonisingly slow when running some apps, including Google Maps. Solved by rooting and installing sysctl config. I’d recommend doing this as it’s made a noticeable difference to the phone, for example the camera now works a lot better.
If you just want an untrashable phone for calls/texts while riding, I’d recommend something like a Samsung Solid.