I love the ending of 'City of Glass' too and I don't want that to be ruined either, but I just took a chance and just read it. I was too excited for it.
For me, it was worth reading to see where the characters were going and what the plot was going to be like in this trilogy. It was darker than the other books and there are new characters. I'm not sure how I feel about this book compared to the others. I might make a decision on that after I've read the other two books in the series since CoFA is kind of the start of a new trilogy in the MI series. But I did enjoy reading it.
There isn't more of Simon's POV than everyone elses. Cassie explains this
link
"City of Fallen Angels, City of Lost Souls, and City of Heavenly Fire are all told from mixed third-person viewpoints. That means some scenes are told from Clary’s point of view, some from Jace’s, some from Simon’s, etc. Much like City of Glass. None of the books are told from only one point of view. None of the books are told from Simon’s point of view only, no matter what you may have heard. They are all mixed point of of view."
Most people from the reviews and comments that I've seen online/on Cassie's Twitter said that they liked Simon more actually after reading the book and that it was a nice change to see how his life is. So I'm not sure if you're opinion will change of Simon, but you never know until you read it. Hope that helped.