Axolotl said:
New Vegas is the same game but made by compotent people.
Really? Because my understanding has been that Obsidian, the people working on New Vegas, are kind of infamous for "flawed masterpieces." Actually, I think that's what the author of the Experienced Points article called them in his last article. They always get some gameplay elements wright, but they fuck up enough of the gameplay elements to completely undo all the good they've done. Their most recent release was Alpha Protocol, and for anyone who hasn't been keeping up with it that was an absolute disaster. It's gotten horrible reviews for everything from bad core gameplay to the fact that it's got a picture in the dictionary next to the word "glitchtastic".
So, Fallout 3. I would highly recommend getting it. So, downsides first. The story is nothing to write home about, but it's not horrible either. It does have a few glitches, though many of them have been patched, and honestly, considering the size of the game it's surprising that there aren't more bugs. Lastly the primary shooter mechanic doesn't feel as good as the mechanic would in an actual tactical shooter (I'm basing this on the console version though, maybe the PC version is better, I wouldn't know), and some of the movements feel off sometimes, though not to the extent that it's a huge detractor from the game.
That said, the game's got a hell of a lot in it's favor. It's got a massive world, there's lots to explore, lots of quests to do, and lots of fun to be had. Admitedly, I feel like Oblivion (A different Bethesda game) did somewhat better on the exploration element (some of the dungeons (or forts in the case of Fallout) start to feel a little bit repetative because for the most part you'll be finding the same guns, stimpacks, etc... as you wander the world, moreso than they did in Oblivion. Still, if you enjoyed Oblivion, you'll probably enjoy Fallout 3, because like I said, there's still lots to explore, and you'll be finding all sorts of fun things. As for combat, while the main combat mechanic, like I said, feels a teensy bit off, the VATS part of combat is a lot of fun (especially if you get bloody mess). The expansion packs are hit and miss. Broken Steel is a great edition to the game, and Point Lookout is kind of like the Shivering Isles of the Fallout 3 world in my opinion. Operation Anchorage isn't a lot of fun to play, but you get some really good items for completing it. As for The Pit and Mothership Zeta, I would suggest avoiding them completely. Finally, as others have mentioned, Fallout 3 has been around long enough and sold enough copies that you'll probably be able to get it for a pretty good price.
So I would say go ahead and get Fallout 3, and if you enjoy it (and personally speaking, I can't imagine how someone couldn't enjoy it) then you'll probably like New Vegas when it comes out, because it looks like it's going to have more of the same.