If you want to change tactics mid battle Skyrim has changed from the 8 choices on the d-pad which I can tell you if you have not played it gets annoying. To a new ‘customizable menu’ to quick select our favorite weapons, spells and items.
The class restriction has gone and its its place is a leveling system that gives XP for the things you do in the game.
Oblivion and Fallout was focused on level 1 to 25 where Skyrim will be to 50. You can get higher of course but it will be slower.
Although this sounds a lot you will be able to level up quicker for each level and have more options to increase health, magic or stamina. Just like Fallout there are also perks to help improve the choices you have made to your character that will effect the game and everything round you.