I can say that I have enjoyed this book as much as the first one, but I must also point out some flaws: the motivation of the characters - especially the earthlings - is a bit disappointing (it reminded me of the horrible movie Prometheus) and as the plot develops it gets somewhat confusing, especially in the ending of the main story (I don't want to go into details). This is something that also happened in the first novel, but here it is more striking.
However, in this novel I think the pros clearly outweigh the cons. As I have already mentioned, the fascinating ecology of Pax along with the personalities of some characters, especially the aliens, captivates you from the first page.
I look forward to this unexpected third novel but at the same time, given the drift of some subplots, I hope it lives up to expectations.
I can read the review of the first novel here.