It's not easy writing a sequel, believe me I know that. Especially when you have new set of characters in the same universe with the same timeline when the first book took place.
Izzat managed to stitch the two stories together flawlessly.
It was a lot to process initially. With too many key characters, I had a hard time to remember which one is which and what happened to them when the characters were mentioned in previous chapters.
You have to be patient when you're reading this book. If not, you will struggle finishing it.
I also wondered why the story was a bit slow in the beginning. But it all makes sense towards the end.
Every single character mentioned is important and I have to give Izzat the credit for making such a brilliant decision to make all characters equally important in the storyline. Everything must have been thought through when he first outlined the story. Now that's not just a character development, but also Izzat's growth in his writing.
There were still a bit of typos and grammatical errors made but it didn't really affect the score I'm giving the book.
I still consider this book to be a good reading.
Izzat managed to expand the Inside Out universe with Upside Down and that's a huge deal, considering how hard it is to write a sequel of the first book that had already have a good ending.