There are a few games that I will buy, even knowing how crappy they probably are. I bought this and Samurai Shodown Sen for the 360, although I waited until I could pay under $20 for each. If Marvel vs. Capcom 3 turns out to be a huge mess, I'll still buy it at some point.
I think XII is kind of fun to play, at least locally. There probably are very few online players at this point, anyway. It is a huge letdown as far as variety and longevity. Hopefully XIII will be a lucky number for the series, and will realize the potential that we hoped we'd see with XII.