"She was a Shadowhunter, and pain was something you lived with."
There's such a divide between my feelings towards the first and second half of City of Ashes
THE MESS OF A FIRST HALF
The main characters got on my nerves. Clary is a typical Mary-Sue YA protagonist who does lots of stupid things. Jace is an arrogant jerk and his tragic past does not excuse his terrible behaviour. Simon is so whiny and annoying. I just couldn't deal with them. The characters that I do like, Isabelle and Magnus, don't have enough page time or aren't developed enough.
The plot is slow, boring and snooze-worthy. There wasn't any urgency towards the events that were taking place.
WHY THE SECOND HALF IS SO MUCH BETTER
The main characters become more bearable and seem more developed, but they still aren't developed enough. Clary is still doing stupid things, but I'm excited about where her new-found abilities are going to take her. The fact that she can create extremely powerful runes elevates her to badass levels. Jace is still a jerk, but he becomes less walled-off and shows more vulnerability. Simon probably goes through the most in terms of his character arc in City of Ashes and I'm really interested to see what happens to him next. He becomes a vampire and then after drinking Jace's blood, he becomes a vampire who can walk in the sun.
The secondary characters also become more developed. The Inquisitor is quite cruel and patronising and her hate for everything and her I'm-always-right tendencies are unwarranted, but I could still understand where she was coming from. She also redeems herself in the end. Isabelle, my favourite Mortal Instruments Shadowhunter, shows just how awesome she is and her loyalty is unshakable.
The plot starts going somewhere and everything comes together and makes sense. Everything becomes so intense and towards the end of City of Ashes ,the battle on the ship, I was worried about the characters and anxious about what would happen to them (and I've read City of Ashes before, which means that I knew what was going to happen, so I had no reason to feel that way).
THE CHARACTERS THAT MAKE BOTH HALVES AWESOME
1) Maryse Lightwood. She's such a strong and fierce woman. I really like the fact that she might not be a warm person, but she's still an awesome mom.
2) Luke. He's an amazing father figure and a wonderful character. Also, the fact that he's been in love with Jocelyn for such a long time, but never told her or pushed her into a relationship... WHAT A GUY!
3) Maia. She's gone through so much and she's so tough.
3) Magnus Bane. He's a powerful warlock. He's sassy. He likes glitter.
THE ROMANCE STUFF THAT RUINED EVERYTHING
The love triangle which I honestly don't care for.
The whole forbidden love going on with Jace and Clary... I don't get it and I don't think I want to get it. Jace and Clary admit that they have feelings for each other and Jace even wants to have a secret incestuous relationship with his sister. SPOILER FOR CITY OF GLASS-->I know that Jace and Clary aren't really siblings, but they don't know that.
TL;DR
The first half of City of Ashes is really boring and the characters grated on my nerves, but the plot picks up in the second half and the characters grew on me. Some characters are awesome in both halves of City of Ashes. However, I am not a fan of the forbidden love angle and the love triangle.