I tried today,
the new weapon unlocks are all there, though they really aren't that great (mostly a bunch of rifles from the G36 family)
You can't use flash bangs, gas, or hooks/zips in the old maps, but this makes perfect sense to me and I don't think you should be able to, these are weapons equipped by SPECIAL FORCES units not the standard soldiers.
As for the half ass integration comment, I don't really get that at all... its EXTREMELY well integrated into the regular game, one of the best jobs of adding an expansion pack I've ever seen. All the paranoid wories about losing ranks, stats, being able to play old maps, etc... all gone.
The ONLY two problems I have is - when joining an old map server it actually closes BF2SF down and automatically restarts BF2, not a big deal but kind of an annoyance, and the loading and wait times on the new maps were ATROCIOUS last night, I even got kicked a few times for idling while verifying client data, but people tell me that was just because the servers were just put up and hadn't started functioning right? I wouldn't know, I don't know jack about computers. I had wicked lag in the 64 players maps, played great with 32 or less.