1. Clary was all shades of annoying, being overly impulsive and angsty by turns. She eventually turned out to be a less irritating pain in the arse, but it took a while. And in the great tradition of YA heroines everywhere, is TSTL (too stupid to live) and blind to obvious traps/manipulations.
2. Jace needed a punch in the face, seriously I have not met a love interest so annoyingly mopey in a long time. Good god, why did Cassandra Clare dump this guy on us? There is nothing, and I mean nothing redeemable about this guy. He did improve slightly at the end of the book, but I wanted someone to punch him into the middle of next week,
The other characters were great, as seems to be par for the course when the two mains aren't up to snuff.
So, why am I continuing? simple, I like the world and the ideas. Cassandra can write without resorting to teen-speak and manages to cobble together a coherent plot, backstory and world. I also like the other shadowhunters.
So it only merits three stars. I will read the rest of the series but something has to happen with Jace and Clary, (namely they need to become mildly interesting/less punchable) in the last three books.