There could be some more explanation and a multiplayer mode, but all in all SpongeBob SquarePants is a cute SpongeBob microgame collection with a lot of speed and fun.
Overall, while this won't be anyone's number one game on their shelf, Spongebob Squigglepants is a fun game to play, provided you aren't expecting more than a Wario Ware 'clone'.
While I'm still not sold on the idea of yet another Wii peripheral making it into millions of homes, I don't think that's through any fault of the UDraw tablet, which works flawlessly and winds up being a lot of fun to use. Spongebob Squigglepants is a great game to showcase this device, especially with the huge number of ways it uses the tablet and even pokes fun at other, more "mature" video games now and then.
As far as reflex games, this isn't too terrible to play. Each "beat 20 games" setup has its own personality and artistic style - along with some fitting and pretty cool music to match - so it's not a total loss.