I do! Their standard lib replacement was used on the project where I originally learned ocaml, so I have just always used it. You have to be fairly sophisticated at reading fn signatures to find things sometimes but otherwise no complaints with it. It has some very nice features too for example convert functions to/from sexps for all base types can save you a ton of time if you know it's there and plan for it.

I've used some of their other libraries too, their logging and unit test ppx are common maybe even de facto standards as much as the ocaml world has such a thing. I've also used, off the top of my head, their code formatter, one of their test frameworks, their implementations of some advanced data structures.

Sometimes you do run into one like the other commenter said, where that shit just does not work. It depends on an undocumented something they shipped separately, or needs a secret bit of config or whatever. These aren't malicious, I open a ticket and come back in a year or two often they'll be working.

It's not zero frustration but I appreciate their approach of just throwing everything over rather than spending more resources testing and polishing fewer releases. Their code quality is generally very high and even if I can't get something working directly, it provides a rigorous & vetted example implementation.