(There be, slight, spoilers ahead. Ye be warned.) 
 Unearthly was an absolute joy to read. Such a fun ride. The protagonist, Clara, actually stood out, was interesting (she even had hobbies! she actually did things!), and was smart (and it was shown, not just told) and responsible. She wasn't unbearably stupid and irritating and bland (like a blank-slate) like quite a few YA female leads frequently tend to be. She was actually a human being with faults and strengths and goals. 
 And... she actually had friends! And a good relationship with her mother! As well as with her brother! She even had a healthy, communicative-orientated, and stable relationship with a boy! *Gasp* 
 That's practically unheard of with YA novels that have female leads, unfortunately. 
 Probably the most surprising aspect of Unearthly was that Kay was never villainized. Yes, Clara tried (slightly) to villainize Kay in the earlier part of the novel, but she eventually realized that Kay was human too, and just because Kay was popular and pretty and dating Christian didn't mean she deserved to be seen as a villain. 
 That's pretty unheard of. We've all seen and read about the popular, beautiful girl in high school, who usually tends to be cheerleader, and she immediately becomes the female lead's mortal enemy (Taylor Swift. That's all I'm gonna say). Especially when the popular girl dates the female lead's crush. The way Unearthly steered away from this was refreshing. 
 The plot was interesting and exciting. The writing was fantastic. The characters, and their interactions, were a joy to read. 
 Now I'm itching to get the sequel.