TL;DR - Great game, but not without flaws
What really separates SSX from its predecessors is obviously the online gameplay, a system called "RiderNet". There are 2 ways to play SSX online, using the "explore" mode and "global events"
Explore lets you quickly hop to any one of the 9 mountains, choose from 1-4 peaks on that mountain, and then choose a track to either race (self-explanatory), trick (score as many points as you can) or survive (complete track as many times as you can given a specific hazard). Each track gives you a bronze, silver and gold time, score or distance you must beat in order to earn that respective medal.
But SSX really emphasizes the online aspect as well. When you post a score on any track on explore, your friends will be notified, and the game will put a bounty on your score, and reward any friends that beat your score with in-game credits (used to buy gear and such). Friends attempting to beat your time/score/distance will also be able to see a a recording of your run (a ghost) as they play, so they can track your progress and maybe take some tips from you.
The next section, Global Events, works similarly, but on a much larger scale. Each track on each mountain works like an event, and any rider in the world can enter the whichever event they want at any time. When riders complete these events, the game saves their performance. When you enter and complete an event, rather than rewarding you with medals based on your performance, the game puts you into a bracket instead. There are 5 brackets, bronze (the lowest), silver, gold, platinum and diamond (the highest). When the event expires (events generally last 1 day but can last for up to 2 weeks), the game checks which bracket you finish in and rewards you with credits based on your performance.
Both explore and global events are 2 great additions to the series. They can be a great way to earn some fast credits, find friends and develop new rivalries. It's clear that EX wanted this game to be more than just a single-player experience, but unfortunately, without splitscreen or real-time multiplayer capabilities, it feels more like a single-player game because in Explore and Global Events, you're not actually playing against anyone in real-time, you're playing against recordings. I'm not very competitive when it comes to gaming, but for those of you who are, this makes it difficult to judge just how good someone is. Since the game only saves your best performance, you don't have much to judge how good someone is, only how good their best performance is.
But enough about the online, i'll get into the core gameplay itself.
One of the most significant additions to the game were the introduction of hazards. Very briefly, on specific tracks lay specific dangers, adding a new aspect of difficulty to an otherwise easy game. These hazards include trees, chasms, darkness, ice, extreme cold and avalanches. There is also new gear to protect you from these hazards, such as armor and wingsuits.
Overall, I felt the introduction of hazards was an interesting concept, but I also feel that EA put too much emphasis on them. The main problem I have with hazards is that they can make the game frustrating at times, as it can be very easy to die from these hazards, especially those bottomless ridges and crevasses they stick right smack in the middle of some tracks. The majority of the tracks have hazards on them, so if you're not the person that enjoys the potential perils of real snowboarding, it can severely limit the amount of enjoyable tracks to play.
Another problem with the hazards is that it feels as if EA included them just for the sake of adding something new to the game, and using it as an excuse to cut corners elsewhere. Many of the hazards are similar, and they take away more than they add on to the game. For example, the trees in the Rockies are pretty much the same as the rocks in the Alps; both are dealt with the same way (equipping armor) and there is no real difference between them. Other hazards are more frustrating than they are fun, such as ice and darkness and some are just a plain annoyance, like the thin air hazard. I do like the addition of wingsuits for the gravity hazard on Patagonia, but adding just the wingsuits would have just been enough; adding a bunch of tracks with huge gaps, holes and crevasses on Patagonia itself just makes the game more frustrating, as it is easy to over/underestimate a jump and completely fall off the mountain.
Another problem with the game I had was with controlling the character. I remember on SSX 3, steering (referred in the game as "carving") was tight and responsive, but in SSX, the steering can feel loose at times, and when coupled with the seemingly randomly placed bottomless holes and crevasses, it can result in numerous, rage-induced restarts of a single level. I can't even count the number of times i've had to restart a race or trick event because I went off a jump too quickly, landed awkwardly against the side of a wall, and slid off the mountain because I was unable to control my character. The rewinding feature does help, but I did not want to incur the time/point penalty. If you're super-competitive and always shoot for the highest score, get ready to restart a lot.
Overall, I felt the addition of the 9 new hazards was implemented just because there are 9 members of SSX, giving each character a hazard they specialize in. A few of the hazards are worthwhile, but I would rather EA just put less emphasis on the hazards and maybe put more work onto the other tracks.
Speaking of other tracks, now i'll get into what I love about SSX. I've already complained enough about the things I don't like, but there is plenty to love about SSX as well.
You can probably tell i'm not a huge fan of the hazard tracks, but as for the tracks without hazards, they absolutely rule. It's hard to describe in a written review, but these tracks offer huge jumps, multiple paths and an exciting sense of speed when you're playing it. Many of the tracks have a main path you follow in order to access a plethora of jumps, grind rails and amazing scenery, but the most important thing here is finding your own path. Most of the tracks here aren't as big as the ones in SSX3, and there's no super pipe challenges, but for the most part, there's always a new way to go through a specific track, and finding the fastest route to go or the route with the most jumps is important if you want to win big.
Overall, I feel SSX is a great game for veterans as well as newcomers to the series. If you can get past some of the repetitive and borderline frustrating new additions, it can be a very competitive and enjoyable experience. Whether you're a veteran to the series or a newcomer still deciding, pick this game up if you want a great game, a great online community and a well-presented game in an otherwise obscure genre.