Had mine a week now. T-Mob upgrade, I got the phone free on £10 / month unlimited texts and data.
Very happy with the phone except for:
1) Terrible speaker quality and volume. All well and good all those saying "use headphones" but that's not much use for ring tones and text alerts is it?! Several times now I've missed calls and texts because in anything but a silent room I simply don't hear it ring. I've complained to HTC who wash their hands of it, and to T-Mob who've yet to reply.
2) Only one way to turn the screen on - power button on top of the phone and unreachable with one-handed use. Galaxy S and my trusty Hero have easily one-hand reachable "home" buttons.
3) Poor build quality. The SIM cover doesn't fit properly, there's a gap, and a ridge on the side. Camera lens is not centred on the iris, it's lop-sided. I've raised this with T-Mob and waiting on their reply. I'm aware of at least one other user with these faults.
Battery life is so far excellent. I've been using it, not intensively but quite a bit over the weekend, it's reporting 8% battery left after 47 hours off charge. That's pretty darn good IMHO.
Overall I'm pleased but I do want to get an exchange handset that's properly put together. Hopefully a custom ROM will sort the ring volume in due course, as it did for the Hero.