Since it's released since today and I spend most of the day reinstalling Skyrim I didn't have an extensive look at it.
My first impression: The first thing that really sprung at me was the fires. They just look sooo beautiful!
It is clearly inspired by NLA, Opethfeldt and Serenity. A little more on the cinematic/fantasy side then Opeth and NLA but not overly so. The brightness seems very well balanced, not too dark but still encouraging torches and light spells. The performance version seems slightly more demanding then Opeth/NLA (which seemed to have the same impact for me), but this may very well also be due to the upgrade to STEP 2.2.9 (distance overhaul for example is new) and upgrading my texture resolution. I definitely have to take a look at sunsets/rises and see how they feel.
If I find out that my first impression is way off I will edit this post.