Maybe. It's not exactly deep or long, but it's certainly more entertaining than the add-ons in previous Pokemon Stadium games. I found it fun enough to merit the purchase, but then I buy pretty much every RPG that's released anyway.
The Stadium/Coloseum section of the game is a step back from previous versions IMO (or at least not a step forward in any real way). Far too inflexible, and does very little to make use of the potential available in a GC/GBA setup.