I like Fallout, but I dislike both Oblivion and Morrowind for 5 reasons:
1. The feel of the game seems off to me, and it isn't very well balanced as far as classes go, it always seemed to me that it favors melee and magic much more than bow and arrow, which is my favorite weapon, so I feel cheated most of the time, since I don't feel I can play the game in the way I wanted to, and that seems wrong with an RPG.
2. This is an issue with almost all bethesda games: HORRIBLE VOICE ACTORS and If not that, the sentences seem fragmented, broken, and odd. And that's not accounting for some of the NPC's suddenly shifting their tone or even gets voiced by a completly diffrent person, it breaks all immersion.
3. This is not the biggest of my complaints, but it is mostly aimed at Oblivion, the interface seems so sticky.
4. Lack of options, yeah, I'm not going to win any favor with this one, I know, you can do a hell of alot of stuff in their games, I'm not trying to refuse that, but the things I want to do, I can't, theres so much potential some places and it just seems wasted alot of times.
5. This goes for all of their games based off of their gamebryo engien, the copy and pasting of enviroments is rediculous, I don't expect every single house to be made from the ground up, but atleast add a little more to each houses than a bit of diffrent loot. This goes for Fallout 3's metro mania as well.