It's a cool idea with a few players in the field. Did a quick check on a WP Blog and the application sandbox keeps crashing. I only have two concerns. You are

It's a cool idea with a few players in the field. Did a quick check on a WP Blog and the application sandbox keeps crashing. I only have two concerns. You are entirely at the mercy of Apple with this product. There isn't too much customization available so Apple may at some point decide to reject your customers apps. A lifetime membership might not help without the code for customization if you ever go offline. The second is the other players in here. I think people are going to want a lot more customization. Either way, you've selected a market with a lot of demand. WPTouch and http://www.wiziapp.com/ http://www.wiziapp.com/ are the main competitors I can think of. (WPTouch built into an app of course)