Just finished reading this. I absolutely raced through the first two thirds, and was totally drawn in by all the different characters. However for me, it fell apart slightly after that. Pages of texts between the law students (are they trainees or law students? Who knows) setting out all their different theories and hypotheses, it really broke the flow for me and I lost track. Also, the "who was killed" and "who is in prison" was relayed second hand, which was a bit of a letdown and took the impact out of it. By the time I reached the end, I couldn't really remember everything from the correspondence and the big "reveal" felt a bit flat.
It has had loads of brilliant reviews, so maybe I'm wrong. I think it didn't help that I was reading it on Kindle - it would have been good to be able to flip back and re-read certain parts. The characterisation was brilliant, and I had a really strong mental image of all the people and their surroundings, even though none of that was explicitly described. I also didn't have a problem with keeping track of who was who, because the characters were all very vivid to me. It was just the last part that undermined it, I thought. Be interested to know what others think.