I'm scared. Usually paranormal books turned to movies--especially paranormal books that revolves around an entire paranormal world--are the riskiest type of movies to make. There are the readers/fan base that will support the movie (well the ones who don't mind the changes) but even then, they still have to draw the mass public. Honestly, the mass public usually doesn't go for crazy things. Shadowhunters, demons, vampires, werewolves all in one place is crazy. 
Harry Potter worked out great because J.K. Rowling had a huge list of "What Not To Do or I Will Never Let You Near My Books Ever Again." And Warner Brothers was willing to risk it all and follow her guidelines, plus it was already pretty popular. Twilight worked because of the MASS fan base and build up. I remember even before the movie came out, the book caught fire and spread so fast. It was weird. Hahah.
But in this day and age I'm sure the industry has caught on to the massive YA paranormal fan base. Especially after the Twilight outbreak they have to had noticed. Half the books being published have some paranormal twist now-a-days. So, I'm not surprised they're putting City of Bones into action. What I fear is what they're going to do. A good director, an average cast and funding will do wonders to a movie, but it's rare getting that much support.
But, like I said earlier, it depends on the audience, who goes to watch it. I mean, they're not making a movie unless they plan to make more than they spend? Right?
