I just finished reading Cassandra Clare's City of Glass, the final book in the Mortal Instruments series. I enjoyed the series quite a bit. Is it my favorite YA fantasy series? No, but I think I like it better than Twilight or the Wicked books that I wrote about not long ago.
The lowdown:
1. The series gets better as it goes. The second and third books were better than the first.
2. The ending was satisfying and not too perfect/wish-fulfilling. It leaves some things open but solves everything vital.
3. Despite some flaws, I think the writing style is okay. While I feel Twilight could have used a heavier-handed editor, the Mortal Instruments are generally decent despite the length of each book (500 or so pages). Some people feel the writing is too flowery but it seemed a good middle point to me between ridiculously unreadable and flatly lacking in vocabulary.
4. It's more mature in issues and feelings than Twilight, but less so than the Adult angst-fest of the Wicked series. Forbidden romances of all sorts but done in a way that didn't feel sleazy to me.
5. Yeah, I could totally guess what was going to be revealed about the two main characters by the end of the series, but did I care? No. Sometimes predicting can be just fine.
6. The potential in the setting and plot is certainly there -- it could have been even more fantastic but I'm trying to remember to take books as they come, not as how great I imagine they could have been...
7. The best characters are the side characters! Probably why Clare is going to write an offshoot book on an important character (Simon).
In fact, she's written another connected series called The Infernal Devices, which is a semi-prequel to the Mortal Instruments. The setting will be Victorian England instead of modern New York City. A side character (Magnus) will have a big role in the new series. She has already stated that there will be no more Mortal Instruments book but obviously anything written about Simon would likely guest star some old favorites.
8. The Mortal Instruments was certainly influenced by the manga, Angel Sanctuary by Yuki Kaori. Actually, one of the characters is even reading it during The City of Glass. I
wrote about the manga a long while ago. The Mortal Instruments is certainly no where near as disturbing, it's more like a happier, friendlier, safer version. ;)
And oddly, it also reminded me a bit of certain events in Final Fantasy VII.
So, would I recommend it?
In a nutshell, yes. I would definitely recommend it over that Wicked series. Will teens like it? Yes, I'm sure rabid fan groups are springing up all over. I like it better than Twilight despite some flaws.
Will I re-read it over and over? Probably not. There are very few books I'll re-read (Harry Potter, anything by Tamora Pierce).
With the right audience (= YA fans, people who like fantasy stories with demons/vampires/werewolves/faeries/etc., and those of us who don't mind some ambiguity while the story plays out) it is recommended.