SX Superstar is an overall decent supercross game, but a few minor problems really prevent it from standing out as a must-have game, even for fans of the sport. It has a fairly in-depth championship mode, where you have to literally work your way from the gutters up into the spotlight by winning races and signing contracts with sponsors. There are different types of racing events, ranging from stunt tracks, where the ultimate goal is to perform as many stunts as possible, to Baja racing, which is essentially an open-track-style race that requires you to get to various checkpoints spread out over the environment. There's plenty to do in SX Superstar, but the problems lie in the gameplay mechanics--such as the trick system and camera--which could've used a little more tweaking.
Visually, both the GameCube and Xbox versions of SX Superstar look quite good.
There are essentially three modes to choose from in SX Superstar--arcade, championship, and multiplayer. The arcade mode lets you jump right into a race, but unfortunately you're limited to the tracks that are initially unlocked--you can unlock more by going through the championship mode--so it's really not all that entertaining when you're just starting a game. However, it does succeed as somewhat of a practice mode where you can get a general feel for the game and learn how certain tracks are laid out, especially the Baja runs.
The championship mode offers much more depth than the arcade mode. This mode places you in the role of a completely unknown supercross rider with little to no money. Fortunately, you get a chance to change all of this by competing in a series of races over the course of a season. When you perform well in a race, you'll pull the attention of advertisers, who will offer money in exchange for being able to put sponsorship patches on various portions of your racing clothes. Interestingly, sponsors will offer a variety of different deals--some will give you a one-year contract for a sponsorship patch on your back, while others might give you a two-year deal with winning bonuses and only require a small patch on your sleeve.
SX Superstar can be an enjoyable game if you're willing to work through some of its flaws.
You can turn down or accept offers as you see fit, and while it's important to hold out for a good deal, you don't want to turn too many sponsors away, because you don't know when the next deal might come along. Of course, it's not entirely necessary to get a sponsor in the first season, since you can compete with the bike that you have with no problems, but as you progress further into this mode, you'll find that the default bike is woefully inadequate--you'll have to fork out some cash for a new one, and they're not exactly cheap. That's why sponsorships can be useful. Another cool little feature of the championship mode is that the interface (which essentially shows your living conditions) will change depending on how well you're doing.
The nagging issue with the championship mode isn't the way it's structured, but rather, it's the races. Obviously, there has to be some learning involved when racing on a track for the first time, since you won't know what the general layout is going to be. This is particularly true for the more-open Baja-style courses, in which the checkpoints are indicated by a green arrow at the top of the screen. But this green arrow isn't particularly effective a lot of the time, especially when the track starts branching into multiple directions and it's not entirely clear which path you're supposed to take. Oftentimes, you will go the wrong way and lose any chance of placing in a reasonable spot by the end of the race, and unfortunately, you can't restart the race either unless you want to forfeit entirely.
This is made worse by the fact that the camera often doesn't take a useful position, or at a least position that actually helps you see down the track. The near camera causes the rider's back to get in the way, making it difficult to see. The far camera alleviates this problem a little, but since the rider is still the focal point on the track, it can still be difficult to see what path you're supposed to take or if the path ahead is even safe. The third camera option, the helmet camera, would work well if it didn't respond to the slightest twitch or bump in the ground. On the flip side, this does increase the challenge level, but it would be nicer if the challenge level were connected to the AI as opposed to a perplexing green arrow.