Surprisingly good, really.
Russian IFF don't seem to work as well as US, and their coordination and command-and-control nets are (notoriously) less reliable, yet they still managed to do roughly as well as we do at not misidentifying and firing on friendlies.
I have to assume they've managed workarounds at the lower (read: local) level, which is what everyone does when a technology they have to use doesn't work in all the conditions they encounter, or do all the things they need it to.
I have to assume they've managed workarounds at the lower (read: local) level, which is what everyone does when a technology they have to use doesn't work in all the conditions they encounter, or do all the things they need it to.