Fallout 3 introduced me to the series, but my dad was a big fan of the originals when they were out. So he dug up his copy of Fallout 2 for me, I liked it (even though I haven't finished it because I'm having such a hard time ), and after playing New Vegas, I feel like I understand why the hardcoar fans hated 3 so much.
It was an amazing game, but the atmosphere is so different. The original Fallout series was actually funny, whereas FO3 could be downright depressing. Looking back, I don't like how the Brotherhood of Steel was portrayed. They're kind of typical "good guys." I feel like the Outcasts were totally justified in their decision to leave. The fate of the Capital Wasteland isn't their responsibility, and it's not like the Brotherhood's getting much out of being everyone's babysitters.
The Enclave in 3 weren't even that bad -- Eden might've been batshit crazy, but Autumn thought he was going too far. In Fallout 2, the opening cutscene shows an Enclave squad gunning down an innocent family.
Ranting nit-picking aside, I really did love Fallout 3. It's just now that I know more about what the series was originally, I'm annoyed with some of the changes Bethesda made.