Lots of nostalgia factor to this one, the bosses of the castles are the same from previous games, airships are back, and all the familiar faces from characters to enemies are back too. A lot of the levels have bits and pieces from levels in the previous games too, the first level starts out just like Super Mario Bros for the NES.
In addition to the old stuff, there are plenty of additions as well. There are new power-ups that are really cool, new game mechanics (a little waggling but not much), and multiplayer. A lot of the levels are designed with some of the powerups in mind, and unlike in previous games there will be stuff you can't reach without them, forcing you to come back and play through it again when you have said power-up.
Another new thing is saving the toadstools. Goomba guys will show up and kidnap them from time to time, and take them to a level you have already played through. They will be in on of the ? mark boxes in that level, so you need to go through it til you find them (when you are close you will hear them yelling). There are also plenty of the mini games from past games to get you extra lives and power-ups.
There are a lot of little improvements too that make the game a lot cooler, like if you hold the d pad button towards a wall, you can do a wall jump. You can do as many in a row as you can pull off, so this will save your ass a lot of times if you are quick enough.
The multiplayer is really awesome for this, if you get the game you have to do yourself a favor and try it out at least for a while. You can play up to 4 players (Mario, Luigi and two toads), and it's a blast. There are moves you can do that will make certain parts easier to reach, like on person jumps in the air and the other one jumps up from underneath and hits them, launching them in the air much higher. There will also be a lot of dying taking place, as one of you "accidentally" jumps on the other mid air, or picks the other up and throws them into a Goomba, or throws a shell at them, etc
This is a must have for the Wii, so if you have one, go out and get it!
