I Played Oblivion, Fallout 3 and Fallout New Vegas on PC and had no problem with the UI. You can assign items to number keys so switching weapons is easy. I played Fallout 3 on xbox once and I had difficulty with the controls, and in order to switch weapons I had to open up the PIP boy every time. So I don't think its true that Oblivion's UI is optimized for consoles.