I agree to most of the previous posts, I like the initial idea, I think the fatigue system in mosts games really mess it up more than add to it, so a rather unconventional approach would be necessary. However I also agree that the compulsory eating/sleeping should be toggleable, it not implemented by Bethesda then in a mod, however it's a nice feat when you feel like being extra realistic, (I used the Necessities of Morrowind mod with my later characters just to add a bit more RP to it).
Then there is the annoying "guess I'll have to stare at the dungeon door for a while to regenerate", that should be totally banished. I recognize the statement were Beth said that the fatigue will only diminish by combat-moves (spells/attacks) and I wish it's true, however I can't find that quote anywere.
Well, that being said I hope that either Bethesda make it a good system from the start or leaves it open for the modders to take over.
