I purchased ImpactJS after picking the "Creating HTML5 Games" book about it. I was really surprised with the quality of the toolkit and how responsive the developer is. I think it was the best investment I made this year and I can't wait to release some games.
I'm very happy with impact. It's well designed and easy to extend. After quite a bit of exploring different frameworks and engines (including writing my own), I think impact is my long term game dev solution.
