The replay value is off the chart. This game alone may be a reason to purchase a GBA. I have played card games on the PC over the years that weren't this comprehensive. I highly advise purchasing Ultimate Card Games. It's an instant classic.
One of the very few games that can be considered an absolute must-have Game Boy Advance title This incredibly complete game package is brimming with so much replayability, you probably wouldn't even care if someone permanently superglued this cartridge into the slot.
This is probably the best time-killing game to come along since "Wario Ware Inc"; even if you only use half the content on this cartridge, it's well worth the investment for the hours of entertainment it offers.