Just installed HTC's 2.3, all working fine so far! Just to add my experience....
I have an Orange branded phone, and am sick of the bloatware (game demos, Orange Maps etc). I have I came down this morning to have a go at rooting my phone and maybe installing a new ROM, which I've never done before, apart from on a sony ericsson. Pure coincidence that the HTC 2.3 came out today too. Following the instructions by SURoot (thanks!), I managed to root the phone. I then tried to remove the bloatware with Titanium, which I couldn't get to work at all. I really spent some time working out how to install a custom Rom, and couldn't get my head around it. I'm sure people will tell me it's simple, but I was confronted by tons of steps and kept getting lost.
Anyway, after mulling it over, and reading some responses on news sites saying that people had successfully installed HTC's 2.3, I couldn't resist. It took 10-15 ,minutes, and was a absolute doddle, run the exe, plug the phone in, wait a while and it's done. It DOES wipe the phone (but not the SD card) so save any data.
Impressions after 20 mins or so of fiddling:
1. Startup time reduced from 1 minute to about 15 seconds. Shut down time similarly reduced! Blisteringly fast!
2. Much more phone memory - I've just installed most of the the things I had on the phone before and still have about 65mb spare - I was always on about 20-30 mb free before.
3. Phone does generally seem a little more responsive. Might be my imagination - it's always seemed pretty quick to me.
4. NO ORANGE BRANDED CRAP! The 'now playing' button that Orange hijacked for their bloody music store is gone too - my biggest irritation.
5. Apart from that, can't see a massive difference between 2.2 and 2.3. Slight interface changes, not much else.
6. Oh - the recovery thingie that rooting gave me (by holding down the volume down button on startup) has gone completely. If I press the power button with the volume down button pressed, nothing happens - the phone just starts up normally when I release it. Maybe they've disabled the safe startup thing? No issue for me - never used it until this morning.
By the way - I have sent an SMS and received one back. I didn't have to input any network settings - it just worked.
Obviously people need to make their own decisions having read all the information available, but for me this has worked a treat - much easier than installing a custom ROM and has achieved everything I wanted. If I hit any problems I will report back.
Annoying seeing as it was the main reason I got the app.
Holy moly!! I'll get it in the end! 
