In terms of updating, I didn't have a good dataplan at the time of the OTA, so I didn't do it. By the time I got a dataplan, the update was pulled back. So for now, everyone that has a brand new phone (or didn't do the update like me) are running around on stock DHD firmware.

There are reports of many minor bugs, but most of them can be fixed by USB debugging, and a few tweaks. However, the more serious reported problems (although this first one is apparently most with the 2.2.1 update) are SMS's disappearing randomly, some people have random reboots (apparently if the battery cover is a bit lose, the battery can lose contact). This last one is not really a problem by HTC per say, but it can be an annoying factor. Many people are only getting 10-12 hours of battery from the DHD, but some people (I get this much) get over 30-35 hours from the battery. I'm soon gonna post a comprehensive guide on the battery. I think it has a lot to do with inital conditioning and various minor network settings (and of course, how frequently and how "heavy usage" one has on the phone).

Hope this post helps ^^

PS! First Android phone of my own, so can't really answer the last question. But my father has the Galaxy S, and some friends have some other various HTC Android phones. I'd honestly chose the DHD any time. For me it's fast, reliable, feels good and does the job just as I want it