Guys, chill! This was his introduction to RPGs, coming from tiny, linear shooters where everything is decided for you. If he liked Fallout 3, that's great! Compared to an FPS, Fallout 3 is a shiny golden buffet of story, character, and choice. Yeah, its story falls a bit flat when compared to other RPGs, but you have to do these things gradually. You can't just go from mindlessly shooting dudes in first person straight to the tippy top of the best RPG (isometric or otherwise) list in one move.
Schuyler--Fallout 3 is a great game. The amount you can explore and do and decide over in the game is all wonderful. Why not try New Vegas, experience a new story where you can make even more choices with a similar armament? Was it just VATS you liked, or did you find yourself into the lore? Was it the change to open world that you didn't know you could have, or was it the myriad and varied characters? Everyone here is dumping the RPG list on you without thought to whether it was any one aspect that made you like it so much, and not all RPGs play or feel equally, regardless of how great of a game they are. There's a harsh change in gameplay between Fallout 1 or 2 and Fallout 3 or New Vegas, and that distinction doesn't work for everyone. But hey, glad you liked Fallout 3, at least. You could do a lot worse as an introduction to the genre.