A non bias review from someone who has not played 1 and 2.
Fallout 3 is an ambitiously made game. The size and scope alone of Fallout 3 are ENORMOUS. It is a FPS with deeply customizable character choices and other RPG elements that will make it easily stand apart from a traditional FPS, but also simultaneously differentiate itself from a RPG. In short, the developer Bethesda seems to know what they're doing.
When you first enter the wasteland ruins of what remains from the post-nuclear American devastated cityscape you can really feel the vastness of desolation and destruction man has reined down on itself in the future. Fallout 3 does a great job of making the player feel as though they are really thrust into this situation. Your character's background story is pretty much what yours would be like if you were thrown into this situation right now. You come from a sheltered life where the horrors of post-apocalyptic life are not a reality and do not exist. You are then expelled from that reality of safety and thrown into a dimension parallelled to that existence only in its opposite polarity. So, when your character doesn't know about something or doesn't understand the specifics about the culture's details it doesn't feel awkward for asking questions that other citizens seem to think is common knowledge. Your character's origin makes it so dialogue doesn't seem forced because your character is almost form "another world".
Dangerous enemies surround you at every turn and nourishment is scares and harmfully radiated to boot. The atmospheric perspective in this game is superb. You can be looking off into the distances from a small hilltop and see something MILES into the distance and know that if you started running toward it eventually you'd make it there. The wastes and ruined cityscape are a marvel to gaze at and explore.
You could probably get through the main story line in about 30 hours, or so, if you never diverged from the main quests and routes. If you did this you would be doing yourself a major disservice. I spent just under 100 hours on my first time through and i found myself time and again getting distracted and adventuring aimlessly just off the simple fact that there is SO much out there to discover and you just kinda...go.
The main story line is roughly 10ish quests long. I know 10 quests doesn't sound like many but most have multiple parts and most have several different ways of completing said task. By the time I had finished the game I had completed 26 quests, putting in roughly 97 hours, 107 locations discovered, and like 30 different guns'n explosives that were at full lethality with my characters specific build. Moreover, I know that I had missed many other quests and or skipped some that I had received because of how I knew their completion would have an influence on my Karma (The game's simple morality system). I knew it would be a negative effect to the way I was playing through the story and didn't finish some. In the breath-takingly immersive world of the Washington D.C. wastes you really feel as though the way you choose to execute some quests really have a large impact on the world that surrounds you.
At first this game does feel like an average run-of-the-mill FPS. After getting a few character levels in and starting to tweak your character you really start to feel the RPG. Also, choosing when to use V.A.T.S. (your time-stopping targeting system) is paramount to survival and makes the feel of any run-of-the-mill-FPSnormality fade into the abstract. Also, besides the ability to stop time and target, another factor that makes it feel more RPGish is its expansively gigantic landscape terrain. There is a lot of sub-terrain to traverse such as; subway tunnels, subway stations, underground laboratories, factory underbellies and bunkers or "vaults". These underground environments really give the game a nice dungeon crawling feel.
One thing that is noticeably problematic, and shouldn't be because it has been around in games since Mario has been searching castles to find Peach, is jumping. This is not just me, i have talked to several of my friends that i have let borrow the game or have played it on their own and they all report the same thing. Sometimes the jumping in this game just simply SUCKS and you can really feel it when it's happening. It is a good thing though that jumping doesn't play a big part in this game, but it is a mechanic that is so elementary in video games that it should be mastered; especially when this simple mechanic is surrounded by such other technical marvels.
All in all, this game is an ambitiously enormous adventuring FPS where die-rolling comes into play to differentiate damage you will deal and receive. Fallout 3 delivers to a wide variety of player interests and does so nicely. This game is not a shallow mindless blandly created FPS with no sustenance. Fallout will keep RPGers happy with many different ways to create characters and character-build customization complexities to bring you back for possibly multiple play throughs. It will keep FPS fans happy with gun-pointing-face-exploding-blood splattering-gore-pasted-walls happy-fun-time action. And finally, but not least, the adventures will be overjoyed with numerous places to be explored and to do so in a world where you really feel like your presence is making an impact on the environment and people around you. Fallout 3 is a game where you have been thrown into a post-apocalyptic planet where scavenging, scraping by, and sometimes ruthlessness are the only things that will reward you with survival and you really feel like you are a part of it.