SSX On Tour takes the series in a new direction, and it works really well.
Gameplay wise, On Tour plays exactly like its predecessors, with a few tweaks. The special tricks are now activated by pushing the c-stick in a direction, which allows you to do regular moves even when your trick bar is full. Another change is the new ability to play as skiers. Skiing doesn't play a ton different than snowboarding, but all the tricks are different and its nice to have the option. Also, the Gamecube version has Mario, Luigi, and Peach has exclusive characters, which is pretty cool.
Multiplayer is pretty much the same as the previous games too. Its a standard 1v1 split screen match, with the predictable Race and Trick events along with a few other types. Its not the best in multiplayer, but its still can be fun to play.
Like noted before, the game has a distinct look and feel. It has this crazy notebook drawing menu look, which is both cool and hillarious. In-game, its graphics are great. The detail in both the character models and landscape is good. It also has a great sense of speed. The audio is great too. On Tour gets rid of SSX 3's annoying radio host, and it has an awesome soundtrack too. I should also note that I have not ran into any of the frame rate problems Gamespot talked about in their review.
If you're a fan of the series, then you shouldn't be worried about EA's changes, because they work well. You should still get this even if you haven't ever tried the series before, because this is one of those games that shouldn't be missed.