This is definitely the best extreme sports game on a portable machine. It has all the stuff in the Next-Gen ones, character creation, loads of levels, grinding, grabs (although in cut down form, as you'd expect). Admittedly the viewpoint is still a bit static, but it's much better than the GBC one. It is truly astounding what they've done with this game IMO.
Summary: Great game, must own for GBA owners, fans of the genre or not.
Graphics: 9 (top notch, i'd rate them higher, but it IS on GBA)
Sound: 8 (Lacking in the tune dept, but still damn fine game)