Eh, that was a long glurge but I'm happy to share specifics without the flurid response.
The positives of Fallout 3:
Fallout 3 is a game which benefits immensely from its transition to 3D as the environments of a post-apocalypse society become far more intimate and immersive than a Top-Down environment like Fallout 1 and Fallout 2. We get to explore the interior of the Vaults and experience life in their conformist as well as repressive claustrophic society for the first time rather than just getting kicked out at the start.
The vastness of the Capital Wasteland is something which immediately overwhelms the Lone Wanderer and the player simultaneously when we first enter it. The freedom to explore is encouraged and you are soon able to go across hundreds of spots containing all manner of bizarre and interesting settlements. Fallout 3 is bigger than Fallout 2 which is bigger than Fallout 2 with a mixture of the ultra-serious as well as Fallout 2's particular brand of goofy.
While some people claim the first person shooting system is a step down, I like the fact it encourages you as a survivalist rather than a guy heading up a massive party of people traveling across the desert. You and your dog makes a bit more Road Warrior sense than you, your dog, your wife, and six other guys.
The Mad Max movies were violent and impressive action movies, which Fallout 3 manages to replicate with its battles against the endless hordes of Raiders populating the Wasteland. Environemtal storytelling like the hanging bodies, beers, and general trashiness of their locations contrasts against the scavenger-esque Megaton homes and the spartan military accomdations of the BOS and submarine-esque conditions of Rivet City.
The choice to settle it in Washington D.C. allows the players to explore familiar monuments and locations which adds a kind of "going into the Statue of Liberty in GTAIV" feel as well as underscores this is the ruins of the USA. It also adds poignance to quests like claiming the Declaration of Independence. The use of Lincoln's Memorial nicely dovetails with the slavery subplots even if you want to go completely crazy and dress like him.
There's a lof of great homages to 1950s sci-fi like Them, the clunky robots, and repressive 50s culture. Also, plenty of homages to mad max and more which continues the trends from Fallout 1 and 2 as well as highlights the fact the game was made by true fans of the series. The storyline is a retelling, more or less, of the 1st two games with a rough approximation of the original plot.
Leave the Vault
Water Chip=Water Purifier
Stop the Super Mutants
Stop the Enclave
Music plays a big role in the game and sets a theme with nicely selected classic radio pieces homaging "Crazy" and "I don't want to set the world on fire." Three Dog also gives you a sense of accomplishment with his praise and condemnation.
Combat wise the game also gives a good sense of progression as you go from a helpless vulnerabel Wastelander to a Power Armor wearing badass like in the original games.