We've been using DRF pretty seriously for over a year and have yet to find a feature that we want that isn't already implemented or easy to implement on top of it.
We haven't separated many of our services out but we actually have extended a lot on top of DRF. We created a way to do internal requests, so now instead of passing querysets to HTML views we actually do an internal API call. In the future, that code can be moved into it's own service.
Abstracting things out like this allow us to plan for microservices in the future while not having to deal with tons of different codebases and deploy strategies right now.
In the past year as we've scaled from 3 to 20 developers, I would say that DRF is the single-most crucial element that helped us scale the team without any massive issues.