Inventory management-The way they changed it from Morrowind to Oblivion was bad,as i believe many think as well,even with the idea of making it more streamline and easier for people,the end result was poor,and I'm afraid we might have the same in Skyrim with all this Apple sort menus.
Spell making-Was pretty nerfed from Morrowind to Oblivion,hope it wont be even more now.
Enchantment-Was very good the way we had it in Morrowind,and like spell making was nerfed to the ground,and don't bring the "Was over powered" talk,cause it wasn't in Morrowind.
One thing that i don't remember ever reading anywhere,was how in Morrowind EVERY single npc,even a lousy bandit in a hidden forgotten cave,had a name,and in Oblivion was all generic bandit this,marauder that,i think that was a big big immersion breaker there,really hope thats better handled in Skyrim.
And hopefully better system stability,to avoid all the evil ctd's we all came to hate