Summit: It's like comparing Monty Phyton to Benny Hill
Delixe: I've heard people complain about the writing before but in all honesty the game is so solid and enjoyable you just go with it. It's like an Arnold movie, dumb but enjoyable.
It was pretty bad at times. I remember that confrontation with the "President" and expecting all kinds of awesome dialogue but instead getting, frankly, complete crap. The "kill yourself" thing was more poorly written than in that Star Trek episode from the 60s with the same ending.
I am not one to attack Fallout 3 a lot, I think it has upsides and downsides, areas where it surpasses the originals and areas it lacks, but writing is definately one where it lacks, just as Oblivion lacked in writing. Whoever wrote Morrowind must have left the company, frankly.
I fully expect New Vegas to be Fallout 3 with much better writing and quest design, which honestly sounds like a 10/10 game to me.