Well my take:
Positive:
+++ The world seems full of life which to me is very important in a open world game: children playing, people going about their business, wind in the trees, dynamic day, no loading and so on.
+++ The main dialogue is perfect for me. I could wish for nothing more. It seems fluid and believable from what I have seen so far.
+++ The general graphic is to me quite impressive: houses, people, trees, horses, mountains and so on.
+++ The combat looks fun, engaging and fluid to me.
+++ There's a lot of variations in the world: NPCs look differently, trees, bushes and vegetation seems varied, armor and clothes seems varied and VERY well done. Environments also seems varied without it being over the top which some games can tend to be like.
+++ The attention to detail is mindblowing most places. It really seems a lot of thought have gone into creating this world and every part of it.
+++ Exploration. I get the sense of a world that is worth exploring, that there's something new and exciting no matter what direction I should choose to go. That is to me hugely important in a open world game. That was one of the things I loved about Skyrim, the feeling of wanting to explore to find out what is behind that mountain, what is in that valley or in that cave.
+++ Of the little of quest we have seen and read about in the previews I get the impression that they will be engaging and fun and not generic and mmo-like.
+++ Ambient dialogue seems varied. And so far they seem subtle enough not to distract, but engaging enough to make you feel like part of the world.
Constructive criticism:
--- As others (not all) I think the world is way too colorful and bright. It's not as dirty, griddy and dark as I expect a medieval RPG to be and how I imagine TW world should be like. TW1 was perfect in this regard - dark, dirty and dangerous. TW3 feels more and more mainstreamed in this regard (maybe to appease more pople) which in turn makes it feel less mature and less believable to me. The earlier trailers nailed it but the closer we come to release, the more bright and colorful it seems the game becomes.
--- In turn this brighter and more colorful world ruins some of the atmosphere and immersion of the game to me. Like in DA:I I find it so hard believing I am running around in a world in war, turmoil and chaos, when everything is bright and beautiful. The world should reflect the situation it is in.
--- I miss a few things from earlier trailers, like the pollen flowing in the air and a more subtle sky.
--- The game looks great, but as others have mention the 90 degree walls and other things "ruins" the overall impression, which is a shame.
--- The camera is too close to Geralt for my liking. I hope on PC it is adjustable.
--- Dialogue timing .....Damion talked about it in the live stream, that in certain places you only had a few seconds to pick your dialogue option. That to me is BAD BAD BAD game design.
In general though I am very positive.