agreed. I had to use twisted this year, and I find the whole approach really wrong from an API POV. You have to force everything to use twisted-way, and this impacts a lot the design of the whole app. inlineCallbacks has its issues as well (it sometimes lead to wrong stack-traces, and you are shit of out luck trying to understand what's going on then, but maybe that's just an implementation flaw).

The use of generator has its flaw as well: as pointed already by other, it is difficult to compose them effectively, making refactoring quite a PITA.

Gevent seems like the best option in python, but I have never used it, so maybe it has its drawbacks as well.