I am not going to re-hash what others have commented on here, the reviews so far are a good balance of what the book is about. I am just going to add a few observations.
I enjoyed this book, read it over a period of a few quiet days and it kept my attention throughout. If you are computer literate, familiar with a wide range of computer terms and enjoy crime novels, then you will probably get along with this book just fine.
However if you are not then I would say that within the first 2 chapters you are going to be struggling with some of the terminology and rapidly lose interest before the book has a chance. It gets a bit heavy talking (without any description) about TCP/IP, routing data, Server farms, CAT5 cables etc.
I didn't think that the terminology really added much to the atmosphere of the book and was probably used to its detriment. A little less cyberspeak would have opened the book up to a wider audience.
I disagree with the comment in the product description that "Deamon is to novels what The Matrix was to movies". I don't think this book is that revolutionary or literary changing.
That being said, I read it, I enjoyed it and I recommend it....if you are prepared to just accept techno terms without having to Google them