Fantastic game. It has a relatively high learning curve so you are going to have a hard time actually getting kills after they give you the one "free kill" at the beginning. You are going to have to walk for a long time trying to find a target. Beautiful graphics. I highly reccomend the ATV and Tents DLC if you have the extra cash so you can get around faster.
Most negative reviews are because people think that this is COD where animals run towards you and try to kill you while you drop predator missiles on them.
Just know that this game requires a lot of patience and really takes time to appreciate. Small mistakes will cost you that kill.
My only complaint is the multiplayer. It can be buggy sometimes but for the most part, my multiplayer sessions with my friends have been an amazing experience. The game is constantly being updated so bugs will slowly be fixed.
Overall, I don't think it's a game for everyone. Really more of a niche genre but if you are willing to learn, I think you will like it.