The demo focused on the mechanics of Skyrim more than the story or setting, pointing out the key ways in which it differs from Elder Scrolls III and IV. One of the most immediately noticeable changes is in how it handles combat. Rather than restrict you to a specific kind of character or class, the game lets you fight however you like simply by choosing what you'd like each hand to do. You can do sword and shield, dual wield two one-handed weapons, hold a magical staff in one hand and an axe in the other, have a spell ready in one and a different spell in the other, or the same spell in both to increase its power - the options are plentiful and easy to swap out at will.
Rune magic also makes its debut. Runes work like a magical trap; lay one on the ground and lure your enemies into it - just be sure they're not immune to whatever you're throwing their way. That giant frostbite spider? Yeah, it's laughing at that frost rune it just ran through. Hope you've got a Plan B.
Skills have, thankfully, also benefited from a revamp, and now every skill you use counts towards your leveling, even if you use it sparingly. There's also a perk tree for every skill, which creates even more options for customization. There's so much choice, in fact, that I almost wonder if Oblivion devotees will fall back on what they know from that game, simply because the bevvy of new options is a bit overwhelming.