I already got 60 hours out of that first act before I stopped playing. It's already a pretty great game and tons of fun but at this point I'd rather wait until I can play the whole story. Though with the content they keep adding if you played for a bit and came back later at release it'd probably still feel fresh.
I played through Early Access once (at least until I hit level cap and found zone transitions that were restricted) right after the launch and had quite a bit of fun. They've made improvements I agree with and pushed out another base class (Druid), but I'm still going to wait for a proper release before hitting it again. I'm looking forward to it as much as I was before EA launched, which can't be said for some other EA games.