This is easily a 5 star phone. So ill just focus on the things ive struggled with so far instead of repeating what you will find on internet reviews. (Im just your average consumer rather than an expert by the way)
1. The touch screen is resistive (a particularly good one mind you) , which isnt as responsive at other screens and every so often you will find yourself having to tap a couple of times for it to register. There is a stylus, but you wont need it too often (ive only used it for the chess game). You will get used to the screen so i dont think its a critical factor, but its one of the more noticible differences with similar phones.
2. The screen is also smaller and lower resolution than other major phones, but fret not, you are not likely to notice. Media and the menu system looks great.
3. I struggled to put media onto the device to start with, my one sometimes confused some music files for video (a mistake my psp doesnt make). File organisation i found to be abit sketchy also, it tends to just list videos (although music orgainsation works fine).
4. Devise, although well built, feels very fragile. I particularly bad fall id imagine could damage it more than my battered HTC dream. Some sort of case would be a good idea.
5. Internet connection tends to be abit hit-or-miss, i have a tmobile mobile internet connection but for some reason seems to be slower than using it on my HTC dream. Perhaps i had a poor signal, i dont know. The browser can be a little inprecise at times but ive come to expect that from smaller screens.
6. Keyboard is definatly a plus but it is quite narrow.
7. Portrait screen mode only when using the phone function, i think there might have been a update for that but i dont know how to change it.
8. you might need to refer to the internet for information about some of the more obscure funtions (like sync-ing contacts and emails).