I bought one of these off-contract. Yes, I paid full price. I wanted a Windows Mobile 6 phone (for the range of apps available) with HSDPA and a vertical keyboard (as opposed to one that slides out along the length of the phone) in a reasonably small form factor. This was the one that ticked all my boxes.
First, this doesn't have WiFi, which for a lot of people is a show-stopper. I don't have wi-fi access most of the day, and when I'm at home I tend to plug in my phone to sync so that wasn't a problem for me.
Responsiveness is OK, I guess, *for a Windows Mobile* phone. Every WM phone I've used has been a bit sluggish, but I accept that as a trade-off for the range of apps available. And this was no exception.
Signal strength is good, call quality is OK (not stunning as I've since found out since I got my HTC Magic, but I never noticed it to be problematic). The keyboard is a bit fiddly, but these things are very much horses for courses. The buttons are very small but reasonably well-spaced and offer quite a bit of resistance, whether that suits you or makes it unusable is going to be very much down to whether it fits your thumbs! It has a jog-dial (the big circle under the screen in the photo) which is good for scrolling down lists or web pages - a good feature, I think.
For me though, the killer (and I mean that in a bad way) was the touch-buttons either side of the jog dial. For me, these are WAY too sensitive. I found it very difficult to do much with the phone - especially if I was using the jog dial - without accidentally brushing against one of the buttons and switching to a completely different screen mid-function. WHICH MADE ME WANT TO DROP-KICK MY PHONE ON SEVERAL OCCASIONS!!!
Again, I think this is going to be very much a personal thing though - if you tend to be quite precise with your keypresses, you might get on with it just fine and wonder what on earth I was talking about. But I'd suggest trying one out before you commit, because for me this was a showstopper.
Otherwise, it's an OK phone. The specific set of features was what made me buy it, because there wasn't anything else similar on the market (and still isn't as far as I know). The build quality is reasonable, battery life is not bad (but not great either), and I found the screen to be bright and sharp. I hardly used the camera so I can't really comment on that. The phone uses a proprietary adapter for both charging and headphones (and the supplied earbuds are just as bad as everyone else's) so I ended up using my bluetooth headset instead - which worked just fine. Video playback was too choppy to use - I suspect this might be because it was too slow reading the SD card, so with a better card you might have a better experience.
One other bright spot - the phone comes with Opera for browsing the web, which I much preferred to Pocket Internet Explorer.