as we recently found out, choosing a framework for GAE can be a costly and frustrating affair. for various reasons we decided to go with tipfy (http://www.tipfy.org) for one of our projects. at that time the tipfy framework version was 0.5.9.
GAE has evolved and i guess tipfy had to catch up with the new additions.
the current version of tipfy is 1.0b1 … the source layout has completely changed which means we have to spend effort to make it work with the latest form it has taken.
the maintainers of tipfy clearly don’t think backward compatibility or easy porting an issue worth consideration. we have since decided to do away with tipfy and port it back to vanilla GAE. from experience the only thing we will miss is the jinja templating which was superior to the django template engine a year or so ago. in fact more important (from our requirements point of view) things like the google map reduce functionality should work out of the box – it was a royal pain to get it to work on tipfy. the tipfy implementation appears quite weak.
our recommendation for anyone out there trying to choose a framework to start on GAE is to stick to the core GAE itself and at the most venture into django.
of course, we welcome tipfy experts to educate us on what we are missing. but for now, tipfy is not yet mature for serious development.