Apparently, they aren't 100% arcade perfect. I love them, though. I have to admit that I really like the new 2k1 backgrounds. Do they fit with the character sprites perfectly: no. But they work better than any other hi res/3D/any other kind of graphical update on backgrounds I've seen in a 2D fighter, imo.
I think they look better than the backgrounds in the DC ports of '98 and '99, or any of the 3D backgrounds put in the PS2 ports of 2k2 or '03. Or any of Capcom's 3D backgronds in MVC2 or CVS2. Adding different times of day, weather effects, etc., like in older SNK games, was a nice touch.
And they play close enough for me. Too bad they're censored, but it doesn't kill the games.