I personally have never read the book, so going in I had no expectations. I was disappointed to find that this show was extremely corny with some seriously mediocre writing.
One thing I did like about the story is that it was fairly fast paced and dove right in rather than dwelling on unimportant details in the pilot. The story itself has substance, and I would like to see how the story unfolds in later episodes.
At some points I just have to cringe at some of the dialogue because of how poorly it's written and acted out by the actors. I found the main character, Clary, to be bland and uninteresting, (like I stated earlier, I've never read the books so I'm not sure how much of this is the show and how much of it is her characterization from the book.) The special effects have to be one of the worst parts of this show. They come off as campy and cheap. The fight sequences are cringe worthy, and overall blah.
I hope to see improvement in later episodes, but all in all, the show holds my interest, despite some of its corny parts.