I just found the fact that the enemies were always about as tough as you very annoying. Firstly, there's no real feel of challenge or need to advance, and secondly, there's nowhere to go when you want to just strut around being some kind of mobile disaster, which is always fun
I loved the atmosphere of Oblivion, the music went well with the backdrops, and the outside scenes were gorgeous, but it was easy to get lost outside, since it got a bit repetitive sometimes. I always feel a little bit betrayed that a game which would have been so much fun to spend weeks over took less than 3 days to complete. I did it again and took all the Guild plots and everything, but by then I already knew the end, which sort of ruined the enjoyment. I did get caught up in the story, but it was way way too short.
This is why I plan to get Gothic 3 as soon as funds allow, I'm hoping it will make up for those shortcomings, Gothic 2 was certainly an awesome game