Anecdotally: a lot! I find it very useful for practicing IFR procedures and approaches. You can connect it to an external comm service like Vatsim and a real hu

Anecdotally: a lot! I find it very useful for practicing IFR procedures and approaches. You can connect it to an external comm service like Vatsim and a real human will even give you vectors and clearances! (They, too, are using it for realistic practice for a job with air traffic control)