It's wonderful and entertaining. Though, it is slightly rushed in some areas. The ending would've been better if it had, well, more. The final showdown with The Winter Queen seemed far too easy, too quick. It should've been harder than that.
I still love Seth so much! That will never change. If he was a real person I'd run away with him. He's one of my ultimate favorite fictional guys.
Donia happened to be my favorite character this time around while before it was Aislinn. The later was a bit too whiney for me. If I got the chance to live forever and be a fairy queen I'd be happy, yes it would suck to have all your friends and family die but you'd get to be with all generations of your family.
Overall, I'd recommend it to anyone who loves fairies or urban fantasy. It's a quick read that you'll enjoy immensely.