The trailer didn't feel a bit generic, but that is how it was intended to be in my opinion. They wanted to show as many action and magic as they could to make the general audience interested.
Aesthetically feels less Medieval and more like it picked stuff from Harry Potter, GoT and other Hollywood fantasy productions.
I have only read the GoT books, but personally I would have called the witcher universe a lot more fantasy and a bit less medieval than GoT.
The Witcher world is still at the highest peak of magic, while the worlds in GoT or even LotR are at a state where magic has nearly disappeared from the world.
Back to the trailer, I doubt it really represents the actual feeling of the series, as what the trailer composed of was actually quite a lot of the highlights of the entire season. Princess Pavetta, the Battle of Marmandal, the Striga fight, the butchering of Blaviken, the fall of Cintra. And all that being condensed into a single trailer will make it look the way it does.
At the other hand we haven't seen much of the quiter pieces of the story and in particular Dandellion hasn't even appeared yet.
There are a few things left in the trailer that I wonder about:
-the destroyed carriage with the Lyrian Eagle on the guards shields. What is that?
-the council of the 12 persons sitting around a fire. Any clue who they are?
-the tree Ciri is looking up to. I don't remember that scene at all
-what scene is the woman in red running through the woods? I first thought it was Ciri in Brookilon, but neither Ciris clothes look the part, nor does the wood look similar
-is the island with the bridge supposed to be Thanedd? it really feels completly different from the books, so I wonder if that is Cintra?