It's been a year since I've had this phone now.
Once the performance problem was fixed by removing my Facebook account, it became a lot more useful than it had been. Still not great, but a lot better than it was before.
Recently, the phone has started spontaneously rebooting itself at roughly 10 and 20 minute intervals. There it, just sitting on the desk apparently doing nothing, and then the screen will flash on and it reboots. Seems to happen in batches where it will reboot a bunch of times, and then nothing happens for a few hours.
The primary culprit at the moment is Google Voice, which is the only app that I've installed recently.