It's been pretty good with PyTorch. The API has been fairly stable and I've adopted code developed from 0.4.0 to 1.0.0+ with barely the need for any tweaks. Granted, it's a younger project so for now things are stable but maybe 3 years from now they may have some giant API refresh. But I find their API quite nice for the most part so I don't see them needing to switch everything up periodically.
