At work, I’ve been giving Flask a whirl, with a focus on building a REST based API emitting JSON responses. A much different approach from Django, much more amenable to building an API to my mind. Much less magic, but much lighter weight. And at least for me, a bit easier to understand how to generate RESTful responses.
The biggest part of the learning curve has been SQLAlchemy. Between the SQL Core for building DB queries, to the object relational mapper (with two styles of declaring schemas no less), to engines, to sessions, there’s a lot going on. Using PostGIS is exacerbating the issue as 1) the geo part needs extensions like GeoAlchemy, and 2) I take advantage of Postgres’ range types, which aren’t baked into SQLAlchemy and are best used with a non-standard operator (@>). So imagine coming to this Swiss Army chainsaw of object relational mapping system and you’re immediately into figuring how to extend the framework. Fun!
Some helpful Flask extensions: Flask-Restless and Flask-SQLAlchemy