To me Fallout 3 actually kind of fails in exploration. One of the things that needs to come with exploration to me is the looming presence of danger and i mean actual danger, like powerful enemies that you can run into that can wreck your shit in early level or even later levels. There's hardly any of that in Fallout 3 because nearly everything scales to your level.
This point was more meant to praise the map design of Fallout 3. While the actual content of exploration can be lackluster, Manyatruenerd raised valid points about how the game encourages you to find your own route.
Either people are super anal about what an RPG is or lore blah blah but I think its a rather fun time even with its faults. Certainly not a master piece but not the turd people make it out to be. Certainly more re play value than fucking Skyrim that for sure.
I think Fallout 3 is a good enough game, and in terms of RPGs it's probably one of the better ones.
The problem I have with it is that it's not really good as a Fallout game.
Fallout 1 and 2 often felt more like they were designed as worlds than they were designed for the player. If you go west from the starting area, you would immediately find Mariposa. Mariposa doesn't change locations just because the player isn't ready yet. Similarly if you said the wrong thing, you pissed off the wrong people, the world didn't make exceptions just to give players the second chance.
And it worked. I remember first time I met Big Jesus Mordino in Fallout 2. There's such a build up to him first speaking that you are constantly panicking, hoping you don't step out of line, and you had legitimate reason to fear this, the game didn't pull punches, and there's no reason why this casino filled with mobsters wouldn't turn on you if you insulted him.
Fallout 3 by contrast feels too perfectly designed for the player. There's a town blocking your path and you need to either negotiate your way in or do a quest for them, certain areas are locked off until you are higher level, certain NPCs can't be killed because they are necessary for the plot, you can't piss of this or that town because they are one of two major towns in the games. All of it is just such a railroaded experience.
Plus, I think a sequel should be able to expand the source material. Fallout 3 didn't really add anything interesting to the Fallout Universe IMO. It's just the same villains as last time, with the same good guy faction as last time, with the Capital Wasteland being yet another Raider/Mutant infested hellhole. Nothing unique about it.