I believe it is a terrible adaption. I feel like they took everything I loved about the books and threw it out the window. Now I completely understand that when going from book to screen there will be changes, but they made me hate the show. First I'll discuss the smaller changes. They not only got rid of Simon's band, but they put Maureen - his groupie - in it. His band added to his character. Also Dot was not a sweet lady but a warlock who just threw Clary through a portal with ease. That whole seen in Pandemonium wasn't very accurate. Not to mention Luke doesn't own a bookstore! Instead he is a detective. It doesn't even seem like the same story. I found all of these problems in the first episode. So in my opinion it is a horrible adaption.
However, with all of that said I believe this may turn out to be a good show. If I look at it from a non book lover it looks really cool. There is action, mystery, and romance! It has a storyline that ropes you in from the beginning. So what the acting is mediocre: they can improve.
Now that I have seen some more episodes I still think it's a bad adaptation, but it is a good show. What do you think: agree or disagree? Let me know in the comments!