Wait you need details?? I figured the details were obvious, I suppose not because you are....for lack of a better word, blind. Ha ha. Alright, they added a ton of crap to NV that they did not need (one example is the reloading table). Half the characters have the same voice, the MQ line is not at all interesting, the loading times are longer, 90% percent of the quests are unentertaining (I believe it was Gamespot who first mentioned that), there were various technical problems. I could go on. Gamespot even gave it a 7.5 where as F3 got 9.0. It is not just me obviously. Theres your details. It is like I am arguing with a 5 year old.
1. Well Fallout 3 had 20 quests or something, that was it. New Vegas had hundreds I think with at least 20 good ones for sure.
2. I think Fallout 3 had even less voice actors, but I can't confirm that.
3. The MQ line is a matter of opinion, so that doesn't hold any validity.
4. Loading times are longer because your save file becomes larger quicker in New Vegas because there are more things to do, at least the case for me.
5. My Fallout 3 had more bugs than my New Vegas, so that is also a matter of perspective
6. And finally, I don't rely on websites to decide whether I like the game or not. I bet gamespot gave Modern Warfare 3 a 8-9.5 or something, where I would give it a 6. So again this one is a matter of opinion making its validity much lower.
So you can enjoy Fallout 3 the most, no one cares about that. It is when you start forcing your opinions onto people, and flaunthing your opinions like they are facts when people get annoyed.