no one really bought UMvC3 and based on week 1 sales, it looks like a lot of people didn't buy SFxT as well. of the people who did buy SFxT, I'd described the reaction as lukewarm/mixed, though a lot of people are upset about the DLC and lack of being able to take your buddy online in XBL.
my impression is that no one but hardcore 3S/CvS2/Marvel 2 players really hated SF4 on release. maybe someone can correct me if I'm mistaken. but I believe it was really successful on launch, every update has sold well, and it consistently has a lot of players. people who really dislike SF4 are in the vocal minority I think.
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http://www.youtube.com/watch?v=npHDxSvwCE0