Of course it's strong sales, but it was also extremely front loaded, indicating that it didn't quite live up to the hype. If more people were satisfied by it and spreading their enthusiasm we'd see a longer tail.
Punch Out! was also heavily pushed by Nintendo the same time last year, but that didn't manage great numbers.
A game I'm developing with some friends:
www.xnagg.com/zombieasteroids/publish.htm
It is largely a technical exercise but feedback is appreciated.