I really liked this trilogy. The 1st book is adrenaline, the 2nd is cerebral and the 3rd is ramifications. All are enjoyable and I really appreciate the nuances that Ness adds in. The stakes ratchet up, the tension increases, the death toll climbs (even though the saddest death is in book1 -I am still upset by it-) and the tone gets darker as the series continues. It is a lot like growing up.
I actually think that character building is where Mohanraj really shines. Yes, the world-building is interesting and complex (thankfully we are given the exact right bit of information so that we can follow along and care without getting overly bogged down), but it is the characters who will stay with me.