Playing this now (well, not right now obviously). As with Oblivion, the main problems are with the interface, which is clearly designed for a console. For instance: if you have the temerity to remap the keys (I use arrows not WASD) then the little reminders telling you what key to press for various functions doesn't get updated. And you can't remap the keys before you start your first game. Moving around the map is by pushing the pointer to the edge. The perks screen is all zooming in an out (by moving the pointer up and down the screen).
You have to use the tab key to get out of any function, rather than pressing again the key that took you into it or Esc.
The buy/sell screen is horrible as there's no way to compare your current item with what you are trying to buy. It's also not immediately obvious what is being bought and what sold. It doesn't take long to get the hang of it, but again a scrolling thing.
If you remap the keys like I did you can stop favourites from working, which in turn means you can't equip things to shortcut keys (1-8). And why does this need two steps?
If you do mess up key remapping there doesn't seem to be a "set to defaults" option.
Overall the game looks great and plays well, even on high setting, but there's a lot of annoying little issues.