Which one? The Nintendo 64 one is much better than the GBC one. The Pokemon have their anime voices, and you get to battle as in game people, like Lorelei and Giovanni.
It is very cool. When you really get good, the chains you pull off are just fabulous, because the Pokemon that you are using starts getting all excited.
The GBC one though is a little...slow. Just fails in comparison.
"Play with fire and expect to be burned."