Star Fox: Adventures is a good game, but nothing like the previous Star Fox games. There are very few air missions, and air missions were the core of the previous Star Fox games.
Instead, you control Fox on Dinosaur Planet. This Planet has been broken into pieces, and it's up to you to put it back together.
Fighting the dinosaurs is very easy. Once you get a combo going, it very rarely is blocked.
The game, in my mind, is anti-climatic. The way it ended didn't really fit in with the rest of the story.
However, it's a good game, and if you have a GCN you should buy it.