My god this game is awesome. I must have played like 7 hours of it today.
I've played Fallout 1 and 2 through many times since they came out and I'd easily say they're my favorite games of all time.
I also got bored of Oblivion after about 10 hours. It had more to do with the setting and the writing than anything else though. I consistently saw parallels between fallout and oblivion as I was playing the latter, it's just that Oblivion was sort of boring.
As for Fallout 3, it really feels almost entirely unlike but not completely similar to the old Fallout games. It plays much like Oblivion did, but in the Fallout universe. The combat is very similar to oblivion when you're outside the V.A.T.S system, but when you're using that you can't help but think that this is what Fallout would be if it was real time.
For example, I stumble across two super mutants in the wasteland who are poised to rip my head from my shoulders. Using vats, I was able to make one lose his minigun he was carrying by crippling his arm (no two handed weapons as a result) and the other slowed down because I got a crit on his legs. I thought for sure I was going to die when I saw those Mutants coming over the horizon, because I remember the first time I saw them in Fallout 1 they were such

ing impossible things to kill. I still was way underpowered, but like the old games, you can use targeted hits to swing the odds in your favor. Very awesome.
I think that's the real difference, along with the perks and SPECIAL that makes it just cling onto that classic Fallout feeling. As much as the setting and story ARE Fallout, all those little Oblivion engine things (Glitches, simliar sounding npcs, the control) tend to pull you out of the "This is a Fallout game" mood every once in a while.
The music also doesn't really feel right. It lacks that tribal feeling that the other games had. But they were more about being in the desert and many of the people and locations were tribal. Fallout 3 has a bit more of a modern feel to it. Closer to the old west than ancient native americans. The variety is good, but I was hoping to hear a few of the old tracks from Fallout 1 and 2.
If you're a fallout fan you should buy and play this regardless. Bethesda's effort and ability to pull something off like this with such a huge budget is worth supporting, even if they didn't get it perfect or it isn't exactly like the old games.
If I had my way there'd be a 2D, Turn Based, Isometric fallout as well, but this is a quality product on it's own. Not as good as the originals so far, but still a great, must play RPG, even in this packed holiday season.