This has a nice core idea with insects and humans being used in a different way set in an alternate earth.
The usual enemy is transformed making it seem perfectly reasonable and rational and likeable.
The mixture of a spy thriller with sci-fi works really well, the thriller aspect leading to a very fast paced book with plenty of action and the sci-fi examining a truly alternative way of life.
The characters are well developed and believable, the enemy are given some depth and behave in a perfectly understandable way as do the people in the Hive.
There are complex interactions between the various members of each group as the work against internal and external pressure and this gives the book some nice depth.
The ending is a little too simple, it is consistent and inevitable and there are no surprises, but it is enjoyable.
Certainly one of his better books.