Watching A Film Before Reading The Book (or vice versa)

With the continual onslaught of new films coming out on a weekly basis, there seems to be a lack of creativity amongst the ideas and stories that are created these days. Resulting in the creation of films that have predictable plot lines and characters, and a story that I don't feel attached to.

With the exception of many, the majority of films seem like passable filler between more glamourous, thought provoking work. Why is this? Does the sheer volume of films outlaid these days mean that little work still results in a considerable paycheque? If this is so, then who buys into these films?

So brings me to my point. Films that tend to do the best are the films that are based on books. The ideas, the creativity and full plot are all already there, ready to be pixated onto the big screen. From our imagination, we can see for ourselves how near our imagination was to that of the author, or perhaps the film director.

However, does reading the book prior to watching the film create unrealistic expectations and possible imminent disappointment? I have found this recently with 'The Hobbit'. Having read the book I was excited to see how this was conveyed onto the big screen. Although it is a rather good film, I was left feeling slightly deflated about the whole thing. This is purely because i had read before I watched.