I brought this game the 2 days ago and I have not been able to put it down since, everything about this game screams excellence!
The Single Player mode is excellent as there is always plenty to do you have the main missions with some very creative characters which themselves are very entertaining and humorous. You also have side missions where you can decide whether to help civilians or not and if you do how to resolve them. Another good activity to do whilst in the open wilderness is hunting! There are lots of different animals from Rattlesnakes and Racoons to Cougars and Bear's!
Another excellent mode to the game is the multi-player, whether it's just you or you and your friends playing there is a lot to do. You can take on different gang hideouts, steal some treasure, cause havoc around towns or go group hunting! These are all situated across the map in free roam. I myself haven't been on the tasks you can do in multiplayer yet such as death matches and shoot out's but thats because free roam is so entertaining! In multiplayer you can also form a posse which I have found a refreshing experience as you can decide who's in it and go against other formed posse's in your session.
Overall I believe this game is worth every penny as you will never be bored and could play it long after you have completed the single player, The graphics are immense and everything just excels compared to the games i have played. This has met higher than my expectations and lets hope COD - MW2 will do the same!!