New site looks pretty good and zero bugs for me, it remembered my login as it always has without incident.
Loving the full-text buttons like "multi-quote off". Good color scheme too.
I have one bit of feedback about the V4 skin for the forums.
Above the first post, there's a gray bar with the subject of the post, and a little yellow "collapse" triangle.
The first post has a subject of course, but 90% of the the subsequent posts don't.
So the bar's pretty unimportant (I bet very few people collapse individual posts), but visually it's strongly
separated from the post it 'belongs to', with a thick black bar below and the dark gray background above.
This makes it look like a separate item even though it's just a minor piece of the post directly below it.
IMO these bars need to be tweaked. Most important is to remove the black bar below and make
it look like the rest of the post, a light shade of gray.
I also think you could shrink these mostly unused subject bars to like half their height.
Then each post will look like a solid block of white/light gray, and a single band of black
separates it from its neighbor.
I've mocked up what I mean below.