To me - even though it has the whole "deep 3D environment" thing going on, I think it will still feel like a rehash of the other NSMB games because it's just more of the same. If there were more interesting changes added outside of levels and collectables, then it could be a bit more of an enticing buy, but currently it would just not be worth it.
So... whether you want to buy it or not depends on whether you want to buy it or not?
You should join my Tautology club!
Since I already have the original, there's no reason for me to buy it. I'd rather they make a new game with more interesting features - sure, they can bring back things like the frog and hammer suits, but there's no need to remake a game that wouldn't really benefit from new technology.