Did leo just pop into this thread, announce his disgust at people being able to discuss Wii Play without criticizing it, and pop back out again?
Anyway, it is a tech demo, but that's hardly a thing to hate about it. It's meant to show people what the wiimote can do, and it does a perfectly good job at it. I didn't play it much, but it was good entertainment for the very little money it put me back. Now that I think of it, my parents bought it for me, so I should be even happier with it. =P
This site tracks sales of video games, and Wii Play should definitely be tracked as well. Any "list of best selling games ever, assuming they cost $50-60 and don't come bundled with anything" can obviously omit it, but such measurement of virtual cocks is not the primary purpose of this site (AFAIK anyway).