One Dark Window

This is marketed as gothic fantasy, and while there are some elements of that, it feels more just like a regular fairy tale fantasy. I wouldn't call this a romantasy either. It's there, but it's not the focal point. I prefer that personally, but just an fyi if you're looking for more romance... 
This whole book is completely predictable. There's no intrique, no surprises. The plot twists are not twisting and when they finally happen, you're left thinking “yeah I knew this 100 pages ago.”
The magic system (magic-granting tarot-ish cards) is neat, if underutilized. 
 It might not bother everyone, but I noticed very quickly that the author has a terrible habit of repeating certain turns of phrase, descriptions, titles, etc. (her lips curled, Captain of the Destriers, slick like oil, his gray eyes, among others). It makes reading so tedious. 
Elspeth... in constant need of saving from beginning to end. Everything interesting (and useful) about her comes from The Nightmare: the only remotely interesting character.
If you go into this specifically wanting an easy, light read then I think you're good, but oof. I don't really understand why this has such high ratings.