My thoughts:
It was a pretty well thought out joke. Not so lame like last years "poopgrounds" or the one we got before that ("redesign is here").
The color was indeed a bit harsh, just a tad bit darker would've been better.
Not letting users posts was funny, I guess the BBS Mods had a nice day yesterday. ^^
It also showed that we can (and maybe should) comment on userpages more often. :)
The blocked flash thing wasn't that good, imo. Lots of submissions (and some of them where serious submissions) where hanging in the Under Judgement phase and nobody could vote on it.
Users going all clockday-ish on new submissions was also bad... but at least I got around 40 blams (out of 60, not bad).
The rest: Fake chat, level icons, B/P icons, Whistles, etc. was pretty funny. I also liked the word filter and I was amazed how well it worked. Trying to pass it with spaces (like g a m e) did not work. Changing negations into the opposite was hilarious!
All in all, this China Rules, um, april fools joke gets an 8/10.