I've tried web2py on appengine, its one framework that would eat out your appengine resources very quickly - http://youtu.be/QOhZkoK1Cr8 (that's just two of us hitting the instance, CPU usage - 16% - 20% in minutes)

Other than that, ah we got globals everywhere !! really makes it hard for any sane IDE to understand WTF is going on. Models are loaded alphabetically. I couldn't get unit-tests working sanely (but that might be as the project I work on replaces web2py crud with their own implementation on top of it).

Why not something very simple - Flask or AppEngine. I found writing your webapp in google appengine way more "a good and clean way to go" than web2py.