Well, I have to agree with some posters here. Morrowind UI is definitely the best. With just one click of the mouse you see everything - inventory, skills, spells, map.
When Oblivion came out, I hated it's UI. The tab within tab within tab was a logistic nightmare, but after a while, I got used to it. After playing with Skyrim, I have to say that Oblivion is the best thing ever. I agree what others have said - Skyrim's UI looks way too futuristic, Journal gives you only like one line of text. Somewhere you may scroll, somewhere you can't. It takes me forever to find a certain item. Another thing that pisses me off is that I can't see my health/mana/stamina bars and my weapon/spell equipped. Only compass and those red blops that show enemies. Since when does my compass have a heat radar? What am I, Terminator?
So, for me it goes like:
Morrowind > Oblivion > Skyrim
If it continues this path, I really fear for TES VI.