The problem with Wave was that it requires a network effect to be of any use, and Google was very stingy with invites early on. Interest had died down by the time they started allowing more people to join.

Stingy invites isn't the problem. It was more it offerred nothing new or better.

I remember Google Wave! It felt more like a technology demo than a product.

You probably had a high-spec PC, and were using it with only a couple of friends at a time? Wave was cool but the performance issues from being built on XMPP killed it.

I totally agree with you that Wave was great.

But, regardless of the reason for its failure, it was ultimately a failure, as much as I liked it.