What positive is there about Fallout 3? I liked the general art design. They nailed the architecture and I was generally happy with their 3D interpretation of the world.
But, uh, beyond that? I didn't like the story. I didn't like the gameplay. I didn't like the lore or the worldbuilding. I have probably written long posts about each aspect before, so just a short recap. The gameplay was a clunky mess that did neither RPG nor shooter style well. The story was a random mish-mash of Fallout 1 and 2, with little regard for logic, consistency, or common sense. We gotta go out find dad, then we gotta find the GECK, and then all the cool things you love from Fallout are there! There is the BOS, very different and kinda out of place, but hey, they're cool! There's the Enclave, who have the same evil plot they had in F2, but this time by poisoning the water supply! There are super mutants, because somehow Vault-Tec made them as well in a vault experiment! Haha, Gaaaary!
Many of the locations in the wasteland felt like pointless filler, were extremely poorly thought out, or, while cool in concept, lacked any effort put into them.
That's the tip of the iceberg.