So I finished Fallout around three or four weeks ago now. In a way, I've only finished a third of what it has to give, as I've only finished it on good karma but from what I can see the game itself doesn't change that much if you're on bad or neutral karma so it doesn't matter too much.
Fallout 3, is good. In fact Fallout 3 is the best RPG I've ever played, if not one of the greatest games ever made. It's story is unparalleled, it's world completely immersive and it's combat fresh and ultimately satisfying. I had a lot of fun with Fallout, but as past readers will know, this wasn't always the case.
It took me three new games before I actually got into it, and I think that is a serious flaw on Bethesda's side. See, Fallout 3 has to be the slowest game I've ever played in terms of story and exploration. Once your hooked, this is an absolute godsend because it takes around 36 hours for an average, well rounded play through (no joke), but for fresh faced players like I was it plays like a steam train being pushed up a hill.
Still, by the end of the game you actually do come out the side with that beautiful feeling of satisfaction that you only get by playing an absolute gem of a title. Fallout's post apocalyptic DC literally smolders with life and atmosphere, to the point where you can actually spend 15 hours exploring. The feeling of survival is also one of the most intriguing aspects of the game, with city's being located within beached ships and landmark monuments becoming makeshift outposts. It's as terrifying as it is beautiful, and it is beautiful. Even the games soundtrack, a hefty selection of 1950's classics, fits the style of the game perfectly, and I haven't even begun to talk about the Vaults yet....
In conclusion, if you're wanting a game that will keep you hooked and entertained for a very long time then Fallout 3 is you're best bet. Just be prepared to fight your way through the first three hours, and you'll be fine.