Note: I listened to the audiobook of Soulless, and I'll be continuing with the books in physical form. See comments at the end on the narrator. 
In a steampunked Victorian England we have vampires, werewolves, scientific intrigue, and preternaturals - being who can negate the powers of a supernatural being. It is rare to see this many genres and ideas fused together so seamlessly, but Carriger's world is thoughtfully crafted to ensure that the components mesh very well. 
The narrative is written with a Victorian flair that really brings out the setting of the story, and the characters are well-crafted.
I loved reading about Alexia. It was refreshing to have a 26 year old heroine, in a world where many heroines are in their teenage years. Not only that, but she clever, independent and not afraid to speak her mind. 
My only qualm with the story was in the romance. It seemed forced and childish (in the we're-five-years-old-and-are-going-to-hit-each-other-on-the-playground-to-show-that-we-have-a-crush-on-each-other way) to me. I liked where the relationship went in the end, but it didn't seem like a believable path for the relationship to take. Ah well...
I'll definitely be continuing on with the series, I'm excited to see where the next book takes us.
Audiobook ReviewThe Audiobook was... okay. The majority of the narration was in Emily Gray's native English accent, and it was fantastic. She has a very high air that was appropriate for the writing style and the novel itself.
However, Lord Maccon's Scottish and Mr. MacDougall's American accent made me cringe every time they spoke. To be fair, I seem to have a problem with all audiobook narrators who use American accents and I also just listened to Outlander and Dragonfly in Amber - the narrator of these books has a fantastic Scottish accent, so maybe I'm a bit spoiled? Either way, I think I'll be continuing with this series in book form.