Bethesda have always said that the only thing to be guarenteed in the next E.S. Game is the lore.
This has played through from the first games, Anything is open to change.
I love Morrowind (1000+ hours and still playing), enjoyed Oblivion (500+ hours), and am currently rating Skyrim as the best yet (Although I am still only 30 hours in, but expect this to replace morrowind fully)
I'm just over 200 hours into Skyrim and It's definitely coming close to being my all time favorite TES game.
I actually wish they took some more ideas from Fallout. Perks in those games felt more like actual PERKS. But in Skyrim they seem to be there to increase damage and armor ratings and so on. I would have liked to have the attributes from previous games with the addition of perks which become unlocked depending on certain attributes and skill levels, like Fallout did. Perks shouldn't define your character so heavily by improving his damage output and other things. That's what attributes were for.
For example; If you have agility of over 60 and sneak skill of over 50, you can choose to unlock the silent roll perk. Instead, we have to go through a perk tree which I think is the wrong way to develop a character. Attributes have been a big part of RPG's for many years, why remove it instead of improving it?