So I've had the phone for about a week now. There are some issues I'm working around with Sprint - a long story, suffice to say that I'm having to deal with two phones for a bit here. That aside, the phone is pretty damned good.
I have a few friends with iPhones - including one with a 3G S - and they all seem to agree that this thing blows their phones out of the water.
The keyboard interface is better than any others I've used before. Until now, the best virtual keyboard I'd used was on the iPhone. This one takes all of the good of the iPhone keyboard, and adds on a "learning" ability. It learns your thumb-typing style as you use it, making automatic fixes to typos you might make while rapidly padding out words.
The video playback is simply amazing. When I'm on a 4G network or on Wi-Fi, the buffering is almost instantaneous, even for HQ/HD videos. When I'm on 3G there's a bit of a wait, but once it's done with the buffering, it streams pretty smoothly with great quality.
The rotation to get from portrait to landscape is a little clunky. Sometimes I find myself having to tilt the top back and forth to get the phone to "recognize" that it's been turned sideways. I think it's application-specific, as some applications just pick it up immediately.
The phone's sound quality is superb in all three modes - speaker, handset, bluetooth. The bluetooth in my car picked it up quick and setup was painless. I tried to pair an iPhone with it once, and had nothing but trouble!
All in all, I'd say this is probably the best phone I've ever owned, hardware and OS included.
Software, on the other hand...
The Sprint crap-ware is there, and it's not going anywhere. You can remove it from your home pages, but you can't actually delete it without rooting the phone first, mounting the flash core OS storage and removing it from there. This is, I'm told, a dangerous proposition.
The Facebook application and synch features seem very last-minute and annoying. It doesn't ask you if you want all of your facebook friends in your phone contact list - it just assumes you do and imports them all. This was VERY annoying, considering there's some people on my FB that I'd never consider calling. I stopped using the HTC app and instead installed the apps from FB directly. At least there I can just see FB contacts. Unfortunately, the damage was done to my Google Contacts account, and I now have the unfortunate task of removing a butt-ton of users from that account. Ugh.
I've had a couple of applications simply not work on the phone, even though they work on a standard 2.1 build in an android VM. Not to mention, though I think this is a problem with the app and not the phone, Fennec has no way to actually type anything. So unless I want to just sit there and stare at the default start page, I'm not going anywhere with it. Fennec, for those who do not know, is the name of "Firefox for Smartphones". I know it's still in beta, but no calls to the built-in keyboard libs on the phone? Really??
All in all, the apps that came with the phone are fine, and I like the fact that the built-in browser supports Flash. Without those few minor unnecessary, impossible-to-remove apps, the phone is nearly perfect.