I shall start, the good things the demo cleared up for my character are...
- I will be able to keep my play-style with a shield and weapon + spells reasonable. It was clear that you can swap between a spell and a weapon just about instantly so that I will be able to swap my mace out for an alteration spell and spend just as much time weaponless for casting a spell as I would have in Oblivion. After all you couldn′t strike with a weapon exactly at the same time as you threw a spell in Oblivion anyway, so with swapping being instant but not animated it′s essentially the same.
- I will be able to specialize in heavy armor over light armor, but not just learn 'armor' as has been thought for a while.
- Even if it′s more effective to block on the go I will still be able to block continuously. (Some have thought it would be like charging weapon attacks in Oblivion, that you hold down the button and you execute a block but can′t hold it)
- Spells will be worth casting magicka wise it seems. (Probably since they don′t have to balance the mana VS damage ratio around people customizing the spells too)
- I will be able to throw a light spell at something that is not a live target and have it light up an area for me. (Torches and night eye kinda aren′t my thing and I always felt that the light spell was a bit restricted since it only worked on live targets in Morrowind and Oblivion)
Just things I could think of at the top of my head. Of course there are tiny negative things too but everyone has written about those. I challenge those who post here to post only positive things they learned from the demo that will affect their own first character.