City of Fallen Angels is, in my opinion, the best book in the Mortal Instruments series so far. They keep getting better and better. I won't give away any endings here so it is mostly safe to read if you aren't to this point in the series.
This book focuses a lot more on Simon which I liked. He has a dilemma dating two girls. Since he hasn't had much experience with any girls, seeing a werewolf and a shadowhunter gets to be a bit overwhelming and he of course gets caught and ousted (temporarily) by both. This gives us a bit of humor but we feel bad for Simon at the same time. He tells his mom that he is a vampire and she flips out, forcing him to calm her using his powers but also to eventually move out. His third big problem is that he finally loses it and bites a human in a moment of desperation and is devastated. Devastated because he lost control and hurt a young girl and also full of self loathing because the blood was so good and he felt so strong after drinking it.
Jace and Clary are happy for about the first two chapters of the story and then it all goes downhill from there. We have a few glimpses of togetherness throughout but mostly a lot of angst. Valentine is gone but Jace worries that he will end up just like him, and he doesn't want Clary going down that road with him.
We also meet two new evil doers, Camille, and Lilith, who is one bad ass demon chic. Her ultimate goal is to bring Clary's half demon brother Jonathan (Sabastian) back to life to wreck havoc on the world. She uses both Jace and Simon to do this and her plan seems flawless because both guys are willing to die for Clary, who's life ends up in danger.
I loved the book all the way through and if you are a fan of this series, you will too. I was on the edge of my seat through most of it. However, I would have liked Jace and Clary to have had a bit more happiness together before tragedy struck... again. At the end of the book (without spoiling it) I was ready to scream out of frustration because I didn't have the next book in my hand yet!
I have to say that one thing a stand alone book has going for it is that you aren't constantly banging your head against the wall waiting to see if the main characters will end up happily together forever or not. They either do or they don't or you are left "assuming" what you choose. Series reading, especially YA, constantly tortures our hearts and souls along with the hearts and souls of our beloved characters. Even in T.V. series, it is the same thing. I think back to X-files, Scarecrow and Mrs. King, and Remington Steele (yes, I am old but the example of Gray's Anatomy works too). When you are finally so excited, after waiting season after season for the main characters to realize that they were meant for each other, they finally do, only to have some major explosion or shooting or kidnapping tear them apart again and you have to wait until fall to see what happens.
Oh well, I guess it is just the curse of loving a good series... on to the next book!