Famitsu basically scores it's games out of a possible 40 points. 4 different reviewers each score the game and then it gets an overall score.
So Sonic Lost Worlds must have scored 36/40, which is a very good score. I must say though, Famitsu are notorious for giving slightly odd review scores so I wouldn't necessarily take their word as gospel. I for one am very excited about this game. If it can manage to produce even half of the magic of the Mario Galaxy games then it could well be game of the year.
The reviews have not been good, that's true, but my preorder was already sent out before they appeared. I've played up to the end of the third world and, shockingly, I'm enjoying it. Can't see anything wrong with it. As ever with Wii U games, Miiverse integration helps too.
So far I prefer it to Generations. Others won't but if you like the Wii Sonic exclusives, notably Sonic Colours, I don't see any reason why you wouldn't like this.
The developers must be feeling sorry for themselves today. It really doesn't deserve the pasting it's getting from professional critics.