A very intense, gripping book with both a strong story line and complex, believable, interesting characters. At over 600 pages long, it is a big read. Halfway through, I had to stop to read another book, and I was quite glad to take a break. Nevertheless, it was so immersive that the length was not really a problem. 
I liked the way that the book shifted perspectives, that was very well done. What I didn't like was the lack of punctuation in Imelda's chapters. Although that did give an interesting sort of breathless feel to the narrative, it also meant that my reading was needlessly interrupted as I stopped to work out what was going on. 
There was a lot of violence in the book, sexual, psychological and physical. Although some of it was a necessary part of the plot, that did mean that some sections were not so nice to read. Although I understand why the author did that, I would have been happier if it had been a little less realistic and a little more toned-down.
The humour was great, with dry comments like, "[the teenagers] had sometimes experienced this with adults  - surprise that information that they had made available to be viewed by anybody at any time had, in fact, been viewed by somebody".
All in all, I'm not surprised that it won lots of prizes and it is a novel well worth reading.