I've played every SSX game, even the abomination that was On Tour.
The new SSX axed "Deadly Descents" as its subtitle, because they thought it sounded too serious. This was a good move, as SSX is a lot like SSX 3, the series' [former?] highlight.
There's a new control scheme, and an unskippable tutorial. After you get past the "WHAT THE FUCK AM I DOING" phase, the new control scheme proves to be better than the old one.
The main additions are:
The rewind feature: basically, hold the left bumper to rewind time at the cost of trick points. It does not rewind the other racers in a race. It can save you from death, or breaking combo.
Items: By pressing the right bumper, you can activate whatever item you have with you. My favourite so far is the wing suit, which allows you to glide for a short time. The ice axes can go fuck themselves, though.
The soundtrack is mostly dubstep and shit like that, but it works well for the game. Run DMC's It's Tricky plays when you get into TRICKY mode. It's kind of cool.
Overall, if you enjoyed the previous SSX games, sans On Tour, you should enjoy this game. It has a plot or something, but all the cutscenes are skippable.
Also, there are online challenges, where players can compete to get the highest score or fastest time on X track. There may be some zany limitations, like not being able to rewind, or not being able to use, say, your wing suit.
The achievement list isn't retarded. You should get them at a decent clip. Even the challenging ones should be doable after getting better gear. Hell, beating TREES without the body armour was easy. All I had to do was spam the wing suit.
OH ALSO NO SPLIT-SCREEN MULTIPLAYER