Wintersong is full of beautiful writing, lush atmosphere, and I really enjoyed the first half of it. Enjoyed it despite the fact that main character Liesl spent a lot of time bemoaning her lack of looks, talent, attention from others and how unfair her life is. But whatever, a teen in those circumstances probably would struggle to feel any other way so you can't claim she is unrealistic. Sarah from Labyrinth was a bit of a whiner as well. 
 In the second half she is finally in the Underworld and you'd think things would become dangerous and exciting from there on out. But they don't. The whole story dissolves in one long boring fizzle. Perhaps the message is in keeping with the idea that the underworld isn't romantic or exciting. It's dreary and it sucks. Hence why people generally don't want to be there and those there want out. Circumstances surrounding the nature of the Goblin King remind me a lot of Ignifax in Cruel Beauty. Except Ignifax was naughty and charming and the Goblin King is pretty dull. Ignifax and Nyx had a fun antagonistic relationship full of banter. Everything between Liesl and the Goblin King felt boring, forced, and sad. All in all, it was un-romantic, un-sexy, and un-fun. 
 Liesl flip flops from emotion to emotion throughout. In the beginning she is judgey and rude regarding her younger sister Cathe for no other reason than her sister is pretty and has no interest in music. She is therefore a dumb bimbo who doesn't deserve the attention she gets. WTF? It should be said this girl is kind to everyone including her shrew of an older sister. But once Cathe is in trouble Liesl suddenly acts like she has always adored her for the rest of the book. She also has a thing for this guy Hans, until he likes her back that is. Her decision to join the Goblin King in the Underworld is impetuously done and quickly regretted. Her desperate attempts to get him to have sex with her will make you cringe. Her mood swings back and forth until the end of the novel, on one page she is all 'I'm the Goblin Queen and will never leave my love' and the next she is desperate for her family and her life. 
 Honestly the writing and world-building here is gorgeous and on it's own would get five stars. Sadly it is dragged down by really lackluster characters and relationships.