Setup was a doddle - it asked a couple of questions and set itself up to synchronise all of my contacts, calendar and email from google. It displays the new emails, texts, etc. nicely at the top of the screen. And so far everything has Just Worked.
The only thing it didn't do was support IMAP push email. Which meant that it had to actively check for new emails every 10 minutes. This seemed pretty silly, but a quick check found me K9, a fork of the basic Android email app that supported push mail. Installing that took about 10 seconds, and I then just had to turn off gmail and the built-in mail app and I was all done.
The only quirk that's annoyed me was that on my old phone I could quit my email app when I didn't want to be alerted any more - whereas on the Desire it looked like I was going to have to turn the synchronising off, which is a bit of a pain. However, the only reason I wanted to do that was so I wouldn't be woken up in the middle of the night. And it turned out that I could turn the phone to silent and the alarm would still make a noise, so that works as a workaround. I need to work out what to do in general though, because I want to be wakeable by a phone call in the middle of the night, but not by emails arriving. I'll have a play with the interface tonight and see what I can find.
I'm sure there will be other annoyances over the next few days, but I guess I'll have to wait and see what they are. Because generally I love it.