I think indoor combat is interesting with doors potentially being a signal for player presence (or non-presence), listening for cars and footsteps outside is pretty dynamic, but no one part of it is all that new. It comes together in a fun way sometimes, but that's really the best thing I can think to say about it. The reward system is shallow, and aiming over long distances feels way more realistic than it should (perhaps this is a good thing).
However, the thing that stops me from playing for hours and hours are those times where, while running or driving through a field on a circle-contraction, I start getting shot from somewhere with no good way to tell which direction other than sound, and by that time I'm usually already dead. That's not intense, or fun, and it just leaves me confused. Also, the start-up time from jumping out of the plane, to getting gear, to finally reaching those fun, intense parts can get draining after a while, especially by yourself.
And dying when jumping out of a slow-moving car. That shit has got to go.