The cult of the amateur
Much of what is on the internet is very shallow, but I would say that this book is full of similarly shallow arguments (Keen expected this sort of criticism, so one wonders why he wrote the book at all - it's actually been suggested that the book is a parody). Yes news reports on the internet might be inaccurate, but so might reports on the printed page, and it's hard to see why other avenues should be surpressed just to prop up newspapers' advertising revenue. Wikipedia comes in for a lot of criticism, but in my mind it is surprising how good it is as a source of information. In academia, the internet is blamed for plagiarism of essays and the like, but this sort of copying has always gone on - its more the switching from exams to coursework has highlighted it. In the 'solutions' chapter, talking about what is to be done, Keen seems more reasonable, but that just highlights what a rant the rest of the book is.
Of course there are legitimate concerns related to internet use such as large scale copyright infringement and children accessing inappropriate material, but if I think that if you want a well thought out discussion of this then it would be best to look elsewhere.