well i just spent quite a few hours this weekend playing SA1 and SA2. It's definitely not a 3.5. Even though I hate the hub world, it isn't enough of the game to merit such a low score. XBLA games should not be held to the standard of lets say the latest $60 title. Thats problem #1, and I think the reviewers are also jaded from the last couple of sonic related failures.
Then again, no surprise that there is fanboyism/hating in the mainstream. Has been this way for awhile.