The only way I could be more impressed with Zoo is if the applications had more OOTB themes/styles to pick from (dark, etc). Other than that it is massively powerful. I built a new, fairly complex Zoo application from scratch following their documentation and had it live for my client in less than a week. Other quotes they got from developers were like 4-6 weeks dev time!!
I've been testing the front-end submission on the latest beta 2.1 release and it's outstanding!
Nice job Yoos!