I like their stomp box models (part of GTR3) for all a lot of things that are NOT guitar.
The amp sim is OK, but I don't like the cab sims at all. Combining the amp sim with some other cab sim/IR processor works quite good, though.
I got it as a free extra plugin with my Waves Gold v8 -> v9 upgrade (thanks to an active WUP), but would not have bought it otherwise.
Too many options kill creativity.