I do like expose/exploit concept, I just wish it didn't stun you for 10 seconds and I'd like it if it wasn't a basically a guaranteed kill.
Probably the biggest problem with ground PvP (other than the 10 second expose stun) are the maps themselves. Small dumb deathmatch maps that spawn you in random places, combined with a bad queue system that can leave you twiddling your thumbs in an empty instance.
The actual mechanics are good (except for the 10 second expose stun) but the setting is amazingly stupid, bland and bad.
I don't mind the expose/exploit, it's the hold that's annoying. Also, I'd like it if all weapontypes were viable options for PVP. At the moment you just have to bring a good rifle, or you might just as well equip a spoon.
That aside, I've never had so much in any other game's PVP, I think the mechanics are fine. The setup however is a major issue. When I join a 5 vs 5 fight, I want to have 4 teammembers and 5 opponents. Why is that so hard !?