I updated my ROM from 1.6.2 to 3.1 today...and....
This is the absolute best of the best when it comes to HC builds. Cross-compatability with the 1.1 BL (Really, who needs 1.2 anyways unless you shipped with it.

) and 1.2 BL in the new versions. My personal experience is one of instant love. The UI is beyond words and I can never go back to these hacked "Phone" OS's.
Pros:
Great support (This thing updates frequently! A VERY big plus coming from the red-headed stepchild known as Vegan-Ginger edition. BTW totally didn't see the pun with the ginger/ginger comparison.)
Stable (for the most part...see cons)
Pretty fast for a FrankenROM (No offense intended)
The UI and accompanying default apps (Just look at it...)
ITS FREAKING HONEYCOMB ON 1.1BL! (Nuff' said)
Makes the iPad/Nook peeps jealous.
Cons:
I get the odd Force Close every so often, related to Music.apk/3dGalley.apk. Those are really the only two that are random. I have assume it to be processor related, AFAIK. If I have had the tablet on a while without flushing my running processes or I was browsing a big site, I noticed the FC's start happening. I ran a catlog with adb and saw the ROM constantly clearing memory and performing reclamations, so who knows there...
A really weird and repeatable FC in Google+ app, where if I try to update my status, it will FC immediately. Probably app related, but I dunno.
No hardware acceleration.

HD YouTube is choppy (BUT it works now so...YAY!)
Flash is iffy, even in Opera (but then again, isn't it always?)
No hardware acceleration...this seriously makes me want to punch whoever at Viewsonic or nVidia is responsible for it lacking the proper ASOP driver support.
That's pretty much it in a nutshell here...great ROM and I highly suggest it!
Thank you, XDA, zyhong, beta/alpha bug testers, and all the other peeps responsible for this ROM!