You sum it up nicely when you say "Honestly, there is nothing to do except promote your combat efficiency and test your skills/gear on other players. " I started off just trying to survive the zed. Once you get the hang of it though, it's pretty easy. Even in the latest patch. I 've gotten vehicles a few times but they're hard to keep when you log out. So that just leaves pvp. And nothing else in the game beats the thrill of it.