I'm testing it right now for a small internal project at November Five. I think there's great potential but at the moment it's lacking some essential and basic features which prevent me from using it for larger projects. Mostly because i can't keep track of text styles or the fact i'm struggling with the 'component' feature (='Symbols' in Sketch). Besides that it's also pretty buggy at times.

Being the 'Most powerful screen design tool' is a pretty cool tagline but there's still some work to do to live up to that. Let's hope they do because i'm curious how this 'all-in-one design tool' thing will turn out and if it can really help us be more effective, save time and simplify handover to development.