It looks awesome, I don't even know where to start on this. It's a massive improvement from ARMA II. There are some annoying bugs but at the end of the day, it's just kind of came out, so the bugs will be worked on over time for sure. There are a ton of new features that I really like, such as the different crouching and prone features. The guns, and attachments for them is really cool as well. An issue I have noticed is that grass is a real FPS Killer at the moment. I'm sure you may have heard of PsiSyndicate on YouTube, but he has a killer pc, yet with grass enabled he gets 35-40 fps - with grass fully disabled he gets 75fps. I'm pretty sure this will be fixed though.
All round the game is awesome and is definitely going to get better as patches are released, big improvement from the last game.