First off. The game does not get a 10. To me, 10 means perfect, with not bugs, glitches or problems. In short, it doesn't exist. However, if your could give out partial points, Fallout 3 would get a 9.75.
It is so much easier to list the few problems with the game that I will talk about those first. First, I have noticed some clipping, usually with blood effects that are overlapping other items on the floor. Secondly, I noticed that sometimes (maybe once every few hours) the game with freeze for a second or two, as though the system needs to catch up with all the polygons it has been pushing out. Lastly, there are certain time when you can't kill someone. Example, when you are walking on the outskirts of Washington D.C., I encountered a small kid named Billy, who approached me and asked me to rescue him from the monsters. Well, Billy annoyed me, so I pulled out me 10mm and shot him. He ran. I shot again, with the shotgun. Nothing. I then noticed he had no health bar. He was "unkillable". Oh well. Also, if you are a spray and pray shooter, you better bone up on your melee skills, because you really need to use VATS to keep your ammo up.
Now on to the good. The graphics are incredible, especially once you think of the sheer size of the game, and the fact that you can get to any place you can see. The first time I saw the Washington Monument off in the distance was from miles away, and when you enter VATS and see a critical hit head shot for the first time, you will blurt something out, usually along the lines of "Wow!". Incredible. The amount of customization with weapons and armor is great, as is the various responses from people depending on alignment and your skills. In fact, the sheer amount of stuff you can do might overwhelm you at first, and the seemingly endless little side-treks you stumble on constantly threaten to distract you from your current quest. You could easily spend 80 hours on this game on the first run through. Enjoy.