I just finished the book and I rate it a 4 out of 5, strongly recommended.
The story is intriguing and the plot well laid out. There is a good pace in it, with not so obvious twists and turns, which kept my attention level high throughout the book. There are a lot of characters and it takes a while to get to know them. Some may like this, some don't.
This book could easily be converted into a film without the need to write a script: the book is the script.
A minor negative point is that I found the end to be too open. There are still too many questions unanswered = a hint for writing a sequel or two. First one a direct follow-up of the story and a second one about the aliens, their history (were did they come from) and their future - even if it were a 1000 years later.
Thanks and hope to read you later.