The top down skinny: Awesome
This is the first game I've played in a long time that has all but shaken me from my Bioshock obsession. If you're not a fan of huge, immersion worlds, big fancy graphics, great sound direction and tons of game play, skip it. You may also want to take up stamp collecting, as I'm guessing video games really are not for you.
Truth be told I'm not *quite* done my first full play through. I believe I have opened up the final quest and am deliberately avoiding it, wandering around looking for side quests. All told it will be about 36 hours of game for one run through. I have skipped a couple of options which would have given me even more to do. I have to admit, I don't want to take that final quest in the main chain because then it will be over.
My big complaint would be hand-to-hand combat which is not much changed from the model used in Oblivion. It still feels like a button mash to me. On the other hand, using guns, and especially V.A.T.S. never gets old.
I should point out that I come to this game from being a Bethesda fan, not a Fallout fan. I played quite a bit of both Morrowind and Oblivion, but am only vaguely aware of the Fallout franchise. I suspect this game does a reasonable homage to the series, but am not an expert.
Final thoughts - pick it up.
*My five spot rating system: Meh is the middle rating. It means the game or product may have redeeming value for specific individuals, but is generally unappealing or flawed to the point of making it generally not applicable. The other ratings are Awesome, which means I think your simply nuts if you don't already love it; Not Bad, which means I think it may not be best for everybody, but it's a good production of what it is; Bah, which means I think the thing failed and has few redeeming qualities; And BC3. BC3 is a direct reference to Battle Cruiser 3000AD which is the first game I ever bought that actually made me think the developer was deliberately trying to make me angry. I try to avoid those ones.