Oblivion is fantastic, especially with juuust the right combination of mods (Might I suggest Chargeable spells and Oblvion Xp?)
But, in order to enjoy it properly, you kinda have to segregate yourself from society. The dull, world weary voice that literally everyone has, plus their creepy, staring faces and nonsensical conversations (Dude, as a guard, you are a threat to ME, champion of the world. You did NOT run away from a mudcrab) all remove any connection you could possibly have to Cyrodiil.
Sure, it's fun enough to keep playing regardless, but the problems are bad enough to, maybe, make you think twice about replaying it. I got through it by role-playing as a real person stuck in a video game, not caring who I screw over to get to the top. And I did screw them over, oh yes.
Also, even though it is only a minute part of the game, that one job part in Kingdom Hearts 2 pissed me off to no end. Yeah, I'm pretty sure you can mostly skip it, but if you don't spend an hour doing the same fucking mini game over and over, you miss out on 2 AP.
Oh, right. Anyone play Space Station 13? Example of a FANTASTIC concept, stuck with a poor, laggy engine and possibly the worst community I have ever witnessed. I mean, it IS a SomethingAwful run game, but goddamn, the community is easily dickish enough to put you off playing. Forever.