I was a big fan of Cassandra Clare's other series so it just made sense to jump onto the prequel series, especially as the next book is out in a few months. I should mention to begin with that I adore the whole steam-punk, Victorian vibe in this book so that coupled with the fact that I am already a fan of the world makes me slightly biased, but regardless I think even if that weren't the case I would have enjoyed this a lot. 
 I know there has been a lot of crit that this book is just TMI in period costume, and I suppose on the bare bones there's a degree of truth. We have a heroine who ends up falling face first into the demon world, who discovers she's not quite as human as she thought she was and then we have the rugged, handsome, cold, tortured hero and the solid, reliable friend. It is a very bare bones look at it though as there are definitely parts of each of the characters that don't fit nicely into the Clary, Jace, Simon boxes that people want to fit them into. Will in particular has a much darker edge to him than Jace has for the most part. Even with Jace in his darkest moods he never behaved as self-destructive as Will does at times, or acted as cruelly towards Clary as Will does to Tessa. Obviously there is more to his character than his behaviour and I'm sure we'll find out sooner or later, but maybe it's my love of a tortured hero but I may love Will as much as I do Jace. 
 Tessa I found myself warming to quicker than I did Clary which is a good thing as I think it helped evoke your sympathy and understand her reactions to certain things as she tries to save her brother, unaware of what is really happening. 
 Jem...Jem is a good guy. He's certainly much more likable for me than Simon is and his story is tragic yet I enjoy the fact that despite the angst in his past he's just a nice guy. I hope we don't end up getting a love-triangle in the next few books as it would be amazing to have a nice, platonic male/female friendship where there is no feelings hidden or agenda behind actions. We'll see, but I have my fingers crossed. Of course, since writing this I have discovered that it will be a love triangle which disappoints me for so many reasons - mainly because this messes with the Will/Jem friendship and again, I find it hard to root for a female character who has two guys on a string, especially when the two guys are friends. I know YA publishers 'encourage' their writers to throw them in, but I am sick of seeing them. This is why I don't read more YA books. 
 The secondary characters are fun and flawed and it was great seeing Magnus and Camille make an appearance. I'm a Magnus fan and it's nice to have that tie between the series, although part of me hopes that he's not a major part just because I'm interested in finding out more about some of the new characters like Henry (he's eccentric and bumbling but I kinda love him) and Sophie. All in all though it was just fun. Fingers crossed that the follow up is as good as this was, because I really enjoyed it.