A must have classical game for all calculator owners. Though I suppose the most extreme Tetris players may find it slightly lacking, it is still a "full" tetris game as far as I can see, and behaves predictably and is easy to get familiar with.
Multi-player can be very fun, but its working is sporadic and unpredictable and tends to cause some glitches in the game itself, though I have never seen those glitches extend beyond the game. I would love to see multi-player fixed.
Overall, the game is perfect for the calculator gamer that needs to pass some time, and is, in my opinion, one of the most vital programs to have.