The best thing about this phone is definitely the display. It's extremely high-resolution for the size. The touch screen is pretty good for resistive technology (as opposed to capacitive screens like the iPhone or Pre). The only other resistive screen phones I've used are the LG Versa and Voyager, and it feels like HTC has just done it better somehow, especially with sliding/scrolling.

HTC also did a spectacular job of making Windows Mobile usable with your finger by way of the TouchFLO 3D interface. There is a stylus included that slides nicely into the bottom of the phone, but I've found that I rarely need to pull it out. It's pretty, but it's also very functional as well. They did a great job on the different text input methods that are available as well. The full QWERTY is probably not practical for anyone but those with the tiniest of fingers, but I find the compact QWERTY setup pretty usable. If that doesn't work for you, you can switch to the phone keypad style and T9 it.

The text messaging interface does have a few quirks. When I tap on a message in the TouchFLO interface and it goes into the messaging screen, the keyboard pops up but doesn't want to type in the text box until you hit it. When you do hit it, sometimes you get a little dance where the keyboard isn't sure that it wants to stay up or not. I can usually tap the text box again before the keyboard goes away and then everything is fine, so it is a minor annoyance.

The camera seems to work fine; I've seen a lot of reviews that say it sucks but the performance seems pretty standard as far as most phone cameras go.

Overall, performance-wise, it is not as bad as I was expecting. I've experienced a few versions of Windows Mobile on different devices, and I know how sluggish it can get, but aside from a few isolated incidents where the device just seemed to lock up altogether (prompting me to perform a soft reset), the performance was actually better than other WinMo phones I've used. It's got a decent processor and plenty of memory. It's no 3GS but I wasn't expecting that.

Will be looking forward to my next upgrade so I can experience a newer HTC model, but until then I will be enjoying myself with the Diamond, especially with how cheap I got it without contract incentives.