Funnily enough, I have pretty much the same exact story as your friend w/FO3. I played Oblivion in college and was completely addicted to it so my roommate suggested FO3...played for about 1-2 hours and it just didn't grab me at all so I stopped. My roommate convinced me to give it anohter shot and I got completely hooked.
Re: FO4...it feels like they tried to cobble together poor man's versions of popular elements in terms of the settlement system (minecraft) and the loot system (borderlands) and the dialogue system (mass effect) and none of it works or meshes well imho. Didn't like the shift to the perk system, the voiced protagonist was a mistake, the art style was too cartoony and bright for my tastes, the combat music is overly "epic" and damages the atmosphere, and the majority of the quests continue bethesda's downward spiral of lack of creativity (to me, they peaked w/the quests in oblivion and have gone downhill since). That said, the world is still fun to explore, and the gunplay is much, much, much better than in either NV or FO3. Still a fun game and one that i've spent about 180 hours in, but imo the worst of the modern bethesda games (morrowind on). As much as I just bashed it, it's easily worth 18 dollars, though. Good game, just disappointing in the context of past FO and ES games.