The difference is that I still don't really get what Wave's about, and I think a lot of folks agree. I still remember the first time I saw Google Maps--I got it instantly, and I was blown away. And the intial value proposition of Gmail (a gig of storage) was obvious too.
That happens with products introducing revolutionary ideas ... people don't quite get it ;)
Wave is probably ahead of its time, and also suffers from a poor user interface.