Fallout 3 is such an engaging and fantastic experience that it's easy to overlook its few minor flaws, but they do exist and should be mentioned. With any game of this size and scope, you can likely expect a few bugs to slip through the testing process and that is the case here. I had the game crash a couple times, amongst other small bugs. In all of these cases, reloading the game has been enough to fix the errors and nothing was frustrating or detrimental enough to give me thought of not recommending the game.
The larger, and far more recognizable, blemish in Fallout 3 that all versions share is the animations. Everything in the world, from the fantastic landscapes to the oftentimes over-the-top personalities therein, comes together to create a believable and engrossing atmosphere. And then you'll see a person or animal move and be given a reminder that this is just a game. The way people move is stiff and lifeless and is a stark contrast to the rest of the outstanding look and feel of Fallout 3. This is especially noticeable in the third-person view. It's great for seeing the unique armor you find, but your character moves awkwardly and doesn't even look like he's interacting with the world he's standing on.
