I think there were definitely thriller, or even horror moments in the book in Mirkwood. Tense, uncertain moments, which were both shortened and exaggerated in the film. I was disappointed on how the suspense was made to a minimum. The chapter itself was made ridiculously short in the film. I rather had seen a lengthier scene. So in this case I am pretty sure that this chapter of the book will be better than the film to people who will read it (that is: if they can enjoy tension other then the purely visual. Also: the book featured more suspense in the escape: people did not see that they escaped, they were in closed barrels; the feeling of being seen/caught can be quite haunting, and I prefer Tolkien's writing over 100.000 action moves although there was a lot of humour in the fighting.