The story mode is what I played primarily, so that's where most of my gameplay opinion lies. The structure and plot is identical to SMB2, with one exception: Each of the 10 worlds contain 20 levels each, as opposed to 10 levels in SMB2. It's also worth mentioning that you were required to beat all 10 levels in an SMB2 world in order to move on. SMBD keeps the 10 level requirement, but now the player has the freedom to choose what levels they want to tackle, thanks to each world having twice as many levels than the requirement to move on. I don't think it ruins the overall challenge either; difficulty ramps up steadily over the course of story mode, and players will find themselves being required to work past something they personally find daunting sooner or later, but now they get to pick their poison.

If you've never played Super Monkey Ball, and don't have a Gamecube to get your hands on 1+2, you owe it to yourself to play this incredible game. One of the best arcade-styled experiences out there. (However, if you do have a Gamecube, you're probably better off getting SMB1/2 instead.)