A fantastic RPG, which has some flaws that drag it down some steps from true glory.
That's why I enjoyed Morrowind and Oblivion so much. And that's the reason why I enjoyed Fallout 3 so much. However, there were certain shortcomings in the experience, some which, from my point of view, I couldn't overlook.
But let's start from the beginning. You are a Vault Dweller, meaning you live in one of the Vaults built to protect mankind from nuclear apocalypse. You live your life as any other Dweller would (which is, by the way, an amazing tutorial and character creation process), until one of your friends tells you your father has left the Vault. Here begins your quest to find your father, though you will find more than just your father...
The main plot is expansive, and offers it's good 10 hours of gameplay just doing it. Of course, side quests will improve on this number, as well as on your character level.
One thing that immediately strikes you is just how similar this game is to Oblivion. While this is by no means a flaw, sometimes the similarities are so obvious, you'll think you are playing an Oblivion mod. However, some things ARE radically different, like the combat system, which is now mainly ranged, with reloads and the wonderful, wonderful V.A.T.S.
For all of those who STILL don't know what V.A.T.S is, it is a targeting system that allows you to pause the combat and select specific limbs (including head and torso) from your enemy to shoot at. After you have assigned your action points, then the combat resumes in glorious, gruesome slow motion. It never gets old.
What does get old is the inventory. I passed the whole game with just two weapons, because the others I found were, either the same, too weak or too damaged to be of any purpose. Plus, the overspecialization inherent to Fallout's skill system, makes it difficult to become proficient in all weapon styles.
While it can be good for some, the fast travel option is limited to places you have already discovered, which can limit exploration to people who don't have the patience to walk miles and miles without too much of a bearing. The game world is big, and wonderfully detailed, but everything must be done completely on foot, which further reduces the exploration desire.
But these are all very minor gripes. The severe flaws I commented before are the terrible implementation of human characters and a disappointing ending (which is great story-wise - more on that later).
After all the time that has passed since Oblivion, you would expect some sort of improvement over the emotionless, plastic and terribly lip-synchronized characters on Oblivion. Well, wrong. They all look as terrible as before, which greatly detracts from the experience, constantly reminding you you are dealing with a bunch of polygons. It's a shame, given the wonderful voice acting and terrific screenplay. It's so bad you can many times see that the head has a different skin tone than the rest of the body, and that's just rude. Other than that, the graphics are fantastic, even if some textures look a bit bland.
About the ending. Well, while it is fantastic in the sense that is completely player dependent, it still remains as an ending. You reach the end and that's it. Wouldn't be so bad if it weren't for the fact that the side quests you would normally do to keep yourself from doing the main plot quest are either too darn easy or too darn hard to find. I remember my Oblivion play-through where it took me a nice 50 hours to reach the end of the main plot because side quests kept spawning on my quest log. On Fallout 3 you must talk to almost everybody to get two or three quests, and even those won't occupy much of your time. All this means the game is short, and doesn't exploit the "after-ending, keep playing forever" potential that Oblivion did have. A shame, given the fact that this one is even more free form than Oblivion.
So, that's my gripe.