Fallout 3 is the perfect blend of an RPG Action Adventure.
The story is a tad weak, I admit that the writing isn't very good compared to others but just like the game, it's amazing. You design your own character and then you continue from there on. You get experience points to level up and become more powerful. The story is going to mak you explore the whole wasteland and boy does it pay off. It's going to have many twists and turns and it's definitely going to get interesting.
The graphics are very good, not the best but good and if your computer is a few years old you should be able to run quite well. And the gameplay is also good. VATS, the Vault Assisted Targetting System, lets you pause the world to select body parts of your victim. Then you accept it and pow you shoot or melee with somthing at them. The gore will make this experience great. The environment you are placed in is another good thing about Fallout 3. It's hostile and you're always feeling lonely - even if you acquire a follower.
The only bad thing really is bugs and there isn't even any bad ones from what I know.
Overall, this game is just simply awesome and I recommend buying it.