This is a quick port of the Dreamcast version of Rayman 2. Don't expect to find anything new, because there is nothing. The added 3D is pretty nice though, with some cool effects, and a sense of depth that helps the exploration. A few times I've even used it to help judging distances, instead of relying on Rayman's shadow. Also the game has remained just as good as it's always been. The analog controls work extremely well.
Compared to the crappy DS version, this is a much more serviceable port. But Ubisoft should be chastised for once again not including any extra content whatsoever, because it makes double plunging very difficult for those who have already played the game before, especially with the full price tag. A budget release would have been more understandable. I should also point out that the framerate sometimes drops a bit, compared to the smooth Dreamcast version.
Despite being an old game, it really shows what the 3DS could do with the platform genre, and it helps that Rayman 2 is amazing anyway. Whether you want to spend $40 on a game you might know already, that's for you to decide. But if you have never played it, maybe it's time to rectify that mistake, now with some extra 3D flavor.