For the overall story plot and characters I give this 4 stars. For the execution and actual writing its 2 stars for me. So to be fair lets average out an obvious 3. But if I'm being honest I'm leaning towards more of a 2.75.
Having already read the prequel, The Infernal Devices, I know the writing gets better. So I can only assume it took her a book or two to really work some kinks out. I hate to say it was a bit amateurish because I can't say I could have done a better job of it but that's the only way I can really describe it. (Maybe I'm used to more seasoned authors) There were too many useless words and elongated descriptions that it sometimes made it annoying to read. Maybe if it had been gone through one more time with a good old fashioned eraser I would have enjoyed it more.
But looking past it's flaws such as the over use of "Clary said..." "Jace said..." (Telling us who said what isn't needed as much when only 2 characters are speaking, we get it) the story was well thought out. I actually want to know what happens next and am willing to give the second book a shot.
Lets just hope a certain twist in the end works it self out because its seriously awkward. Like these poor kids need anything else to worry about...that sort if thing can cause some unfortunate emotional scars. I'd probably take homicidal father over that.