I can't speak for the GP and I haven't used Phonegap but the problems I have encountered trying to use webviews in apps revolve around touch latency and animation. When a user touches an element on the screen they expect instant response and I haven't seen that in any app using web technology. Also, animation needs to be comparable to what you see natively. Even trying to scroll images without scrolling the whole view is a recipe for lag and choppiness. I don't want any part of that in my apps.