Missing elements, not enough variety, and far too short makes ZG is a step backwards from the superior original.
Graphics are better, but that's expected when you change from Gamecube to Wii. This is helpful, but still doesn't completely save the game from its negatives.
The gravity turns and boosts are a good idea, and can have a great sense of speed, but they're used in all the wrong ways and worsened gameplay. They also got rid of some details like the manual boost and trick system from the first, which makes ZG force you to count on luck that you hit the 2 button on time, or reach a boost pad.
But the biggest problem is that the game is incredibly short. I finnished ZG within 3 hours, which is saying something when the first took me 5. And the story was completely useless and confusing. The main goal in the story is to simply complete whatever objective it tells you to. There was no point to the story rather than to take up space.
And what makes the game even shorter is the fact that there's no online. The little Wi-Fi tag is only because you can compare track times, kind of like Mario & Sonic at the Olympic Games' record system. Acual racing in ZG might've been able to challenge Mario Kart when it comes to online racing, but Sega had other ideas.
Even though there are secret characters to unlock, they barely make an impact on the game, even though it was nice to add Silver to the game. The soundtrack is also good, but doesn't do much.
While the game has good graphics, a great soundtrack, and some good ideas, it does nothing to save the game from poor controls. weak gameplay, and a rediculously short story with no reply value. You would see most of what the game has to offer in about an hour. Rent it, complete it, and send it back. Maybe Sega will put the "Extreme" in Extreme Gear next time the decide to bring back the Babylon Rouges (which I hope they do).