I don't think this series could have had a better ending. I laughed, I cried, I got disgusted, I cried again, I laughed again, and cried some more. I wasn't a complete fan of this series if I'm being completely honest but having reread the second part (I enjoyed the first half tremendously!) I enjoyed it. I thought it was good but honestly CoHF makes up for the annoyance in City of Lost Souls and City of Fallen Angels. 
 I think it might have to do with the introduction of the Blackthornes and Emma Carstairs--which was my ABSOLUTE FAVORITE PARTS--and the relationship they have with one another. 
 Jace was his usual self and I didn't find him irritating. Neither was clary and she annoyed me several times in the last book. She was honestly such a different character from the first book :) 
 Izzy and Alec were adorable I love their relationship. Cuties! And simon. Oh Simon. He's by far my favorite character of the bunch. I love him. There's a really great quote that Magnus says about him which I can't remember right now but yes! He's perfect. He's just this. Ah. I can't even. Anyways I love him. 
 And I loved the ending. At first I was upset but then I realized that it might be better like this but right at the end it's perfect. I'm sad to see them all go, but their stories are done:)