The casting of the movie is one of the major problems this movie had. Now Lily Collins and Robert Sheehan were perfect choices for Clary and Simon, but that's about it.
The adult cast was amazing. Lend Headey, Aidan Turner, Godfrey Gao, C.C.H Pounder, Jared Harris and Jonathan Rhys Meyers, an incredible group for this kind of movie. Recognizable faces with us supernatural types and talented actors each and every single one of them (except Godfrey Gao who I did not know before this, but he did a great job as Magnus).
It's like they spent their whole time looking for the adults that they forgot about the kids. These kids get the most screen time and you get Kevin Zegers, Jamie Campbell Bower and Jemima West (WHO!?). I'm not a snob for name recognition either because I know and like Bower, but not for this movie.The Hunger Games for instance:
Some of the cast are people that may be seen in other projects like the girl who played Dr. Sloan's long lost daughter on Grey's Anatomy, but a lot of them are not. The thing this movie did right is they got good actors for these roles.
Look at the Divergent cast. Shailene Woodley, Theo Hames, Ansel Elgort, Kate Winslet, Zoe Kravitz, Maggie Q (YES YES YES, sorry I will calm down now), Jai Courtney, Miles Teller, Mekhi Phifer, Ashley Judd, Tony Goldwyn (FITZ!). This movie was cast amazingly from beginning to end, across the board.
This is one of the major problems I had the City of Bones. I did not believe he was Jace. Alec's character was painfully one dimensional, which is not how he came across to me in the books. Lastly the girl they cast as Isabelle. Really? The role did not seem to fit her; I do not think she is a terrible actor, I think they all could do great, just not in these roles.