Good:
1. Awesome graphics and performance.
2. Huge and well designed world.
3. Lots of stuff to do.
4. Great gameplay.
5. Nice OST.
6. Map editor
7. Arena
Bad:
1. Too easy.
2. No sense of exploration. Items should be physical, random and not pointed in the map, to encourage exploration (take some notes from Bethesda, Ubisoft).
3. Lack of destruction and interactivity with the world.
4. Like in most games, money is too easy to get.
5. Multiplayer