I got it the second it came out; so far(I am about to go to the sand zone) it seems full and the same. I don't think it has the new music the Wiiware version has, but it has three savefiles, the (easy, normal, hard) difficulty options, the jukebox, and the ??? which I am assuming is Curly Game. (play as Curly Brace) I think it's awesome to have it portable on my DS. Supposedly it cuts off the edges a little bit, (DS screens are obviously smaller) but it doesn't downsize artwork, and I don't seem to notice it. So far it seems perfect. (A) and (Y) are jump, (X) and (B) are fire. [L] and [R] are to switch weapons, but you can also press start and go the the item menu to switch that way. Select is the Map. I really like how they made it work, and took advantage of the bottom screen.
But really. They wouldn't release some half-finished thing for ten dolla. And it is a 2D, simple-ish game. It doesn't need to be 100 blocks.