I just finished The Bitter Kingdom, the final book in the Fire and Thorns trilogy, and now I'm trapped in a state of WOW and <3 <3 <3 and fangirl squee. I already posted about how I really liked The Girl of Fire and Thorns and loved The Crown of Embers, and OMG OMG The Bitter Kingdom is even better. The perfect end to a smart, beautifully-crafted, fantasy adventure trilogy. Everything about it--the characters, the worldbuilding, the descriptions, the occasional moments of holy-crap-you-did-not-just-do-that--everything is awesome.
Seriously, if you haven't read this series yet then go do it NOW.