Well, this is the first game I've bought for my brand new GBA so I may not be an authority on the machine yet. However, I have a PS2 and this game is as playable as anything on that format.Firstly, the only fault with the game: the colours on some of the tracks is a bit dark considering the fact that the GBA screen is so small- you really have to get the light just right to see everything clearly.
But that is the ONLY problem. The graphics themselves are very well drawn and the scrolling is smooth. The control system is the key to the playability; intuitive and complex, within a few goes you will be pulling off the most insane moves at the greatest of ease- it is very similar to Tony Hawks in that respect, though I think that the fact that it is on a BMX leads to even more impressive stunts.
The longevity is huge. There are 12 levels and each one comes with 10 objectives ranging from collecting spray cans to doing sick stunts and achieving big scores.
This is the game that won me over and led to me buying a GBA. And after Pro Evolution Soccer on the PS2, this is the best console game I've played for a long time!!!