I really enjoyed this and I was so pleased that the trilogy ended strongly with pretty much everything wrapped up. Of course there were some open ends so that the series can continue, and I won't complain about that at all, but as an 'end' book, this is what I hoped Breaking Dawn was going to be with the scale of the battle and chaos. I was going to give it five stars and no doubt I may go back in the coming days and adjust it, but there were a few little things that held me back such as the Mark Of Cain ruin and a couple of Clary 'moments' that kinda irked me slightly. 
 Clary...as with the second book, I still found Clary more than a little annoying on ocassion and I will not lie - part of me was more than happy when Luke and Jace yelled her out at the start of the book. If ever a character needed a slap around the head to snap them out of being self-absorbed it was her and even at the end her talk with Simon about 'make sure you have time for me', is it just me who finds that level of 'me, me, me, me, me' irritating? Don't get me wrong though, for a lot of the book I did enjoy her again. She was a bit more mature and contributed positively more often than not and I thought she was exceptionally good with Jace when he was in his woe is me phase and wasn't needlessly cruel like she had been in the previous book. 
 Jace is still a fascinating character - so dark yet so fundamentally good and I've seen some hints from the author that he's going to be darker in the fifth book, but I hope not too much because he is a good guy and his life has been universally crappy until that point so I'm hoping for some good things for him in the end up. I love a tortured hero, what can I say. 
 The contrast between Jace and Sebastian/Jonathan was a lot of fun and although I anticipated a twist, I wasn't really anticipating that and their showdown, the reasons they were what they were was handled really well. Nature vs nurture had a relevance in a YA novel, who knew?? 
 The storyline of the book - it was dark (extremely so in places) and it was better for it. It was a war and bad things happen, and Valentine was a psychopath and he did some bad things and even his warped justification for it was chilling. Clary thinks something near the end about how can you hate someone for being a monster when they don't even realise they are a monster? And in a weird way that's exactly it. He does these evil things and you hate him for it but at the same time you know he believes he's justified for doing it so it's almost like a sickness. 
 All in all, I thought it was great and I'm really regretting not having COFA on hand to jump straight back in, but I'll get there soon. It was a very enjoyable, easy to read first half though and I'm looking forward to the characters maturing and hopefully growing some more in the second half of the series. The rest of the books have a lot to live up to with this one.