I am using web2py with gae and google datastore in production of custom application , it is a very good framework.
I did made some minor fixes for work good on GAE, work fast and stable, i have published the Web2Py version changes uses on my github soyharso.
The uploads to GAE are fast, the version control app engine is secure, the free tier offer google for tuning your code is excellent, the monthly cost is adequate