I got it the other day and I am loving it. There is definitely a lot of potential for future microgames, especially on 9 volts stages. I would love to see one where you use the hammer from Donkey Kong or an Excite Bike one where you control the angle of the bike after a jump.
I wish there were more modes that had extended levels like the ping pong paddle tower. I would have liked to have see one for the paper airplane or the bicycle one.
BTW, I think the Wario Ware universe would be a great foundation for an animated series if Nintendo so desired.