I haven't played the first two, though I was always vaguely aware of them (I am a godless heathen, I know). I got Fallout 3 earlier this year and just didn't have the time/mindset to take on a sandbox game of that scope.
I did however start a real play through a few days ago, and I'm enjoying it a lot. the mythology of the game is fantastic, and the visuals and sense of humor in them is really stunning.
I played through Fallout 3 the first time and was hooked to play it again and make different choices. I love the scope of the game! As far as visuals go, I thought they were very good despite the glitchy nature sometimes.
If you liked the mythology of Fallout 3, you'd like the first two.
I had a roommate who tried to get me to play the first two for years, and I just never got around to it. if the first two are as broad and open as this one, I'll probably just stick to wikis for the past info ^_^;; there are a lot of games to play, after all.
Also on a side note, I don't know if I could ever play through and not blow up Megaton. Everyone in that town (except Gob, I suppose) is just so rude.
I somehow managed to keep from blowing it up the first go round but I HAD to kill Professor Cromwell (the cult leader ranting in the middle of the puddle) either way. The man would not shut up. I mean jesus, sitting there all day in an irradiated pool ranting the same thing over and over again should make you dead.
Even though I have an X-Box 360 at the house I am more into games like Duke Nukem 3D & Luxor on it. Every time I try to play a modern game I usually end up killed because my first several minutes are spent just standing there trying to figure out the controls.
I do have Halo though still unopened.... I really should try that out.
I know I am going to make the gamers cringe but yep, Halo for the 360 unopened. Along with a copy of Gears of War unopened as well (as I type this on the laptop I see the case over by the TV cabinet just sitting there, calling out to me to rip open the cellophane wrapping).