I'd been playing the tech demo for quite some time, even the original version from 2011, but I bought it about a week ago. Really fun game, since I'm an off-road nut. The best part by far has to be the multiplayer, grab a few good friends, pick a map, go out driving for hours. That's priceless.
It does need a fair bit of work, though. It feels somewhat like a demo still, and can get boring if you're playing alone. The maps also need more diversity IMO, it's just mud, mud, mud, mud, and mud. I'd like to see some rocky hills that require more than just a slightly modified Russian truck to navigate. Possibly even a more international feeling map, something from the Northern US, or Canada, a bit more of a lush forest feeling, possibly some snow mixed in. There's a lot than can be explored with the game, they have the base down, they just need to improve the content quality. That will partially be taken care of with mods, of course, but you can't leave everything up to the community.
Also I feel like the damage deserves mention, I find it entirely too easy to damage your vehicle in a lot of situations. For instance, I'll be driving down a road minding my business, then I go over a tiny bump, usually barely noticeable, yet I get double digits in damage. How is that realistic? I can understand when I plow full-speed into a large rock, but come on. It's a bit comical to me.
Now all of the other features seem to be in-check for the most part, the physics do feel a bit heavy and lifeless at some point. But it's not a racing simulator. I mean, you barely get over 20-25mph most of the time. Yes, the physics can be improved, but the question is, should they? They do what they need to, and I think the excellent physics brought forth by the mud, vegetation, and water's behavior kind of makes up for the lack of detailed vehicle physics.
Overall I give the game a 7.5/10. It's worth the $30 I spent on it, simply because it's one of the best off-road oriented games out there. But I can understand why some people are disappointed in it.