I played Fallout 3 when it came out, and just got bored with it fairly quickly. It's got that Bethesda vibe where everything is great at first, but then you start to get further into the game and everything starts to seem copy+pasted to make the game artificially larger and longer. Is it like that at all? I see it mentioned as a great game all the time, but I also saw that about 3 when it came out.
I've never played 3 but liked New Vegas a lot. Didn't seem repetitive to me at all. It's worth noting that the two games were made by different developers; Fallout 3 marked the point where Bethesda took over development from Obsidian Entertainment. Despite not being a Bethesda-developed game, it's still buggy as hell and the combat is super clunky. But there's some really cool RPG mechanics going on underneath all that
Bethesda took over from Interplay (Black Isle), Obsidian had a lot of interplay/fallout people on staff.
They only had 18 months to make the game. sigh.