1) The game is beautiful and the feel of the environment is awwsome due to it.
2) Due to number 1, hunting with a weapon for skins and whatnot, especially with a recurve bow is a super duper experience.
3) Overall good graphical options to choose and tweak in the PC port.
4) Overall good story and good presentation of it.
5) While CO OP feels a bit restricted at times(where you can go) its still very fun and at times pretty darn difficult to complete(yaaa

)
6) I like that the unlocks you get in MP carries over to CO OP and back.
7) While I haven't used it yet I like that there is a map editor for custom maps.