Screen adaptations are never a carbon copy of the books upon which they are based. There are always differences that may, or may not, be interesting in and of themselves and would be more effective the first time without any foreknowledge of them. An original screenplay should offer many more such moments.
I don't mind a few hints about a film or book and I won't avoid seeing a film or reading a book if it's been "spoiled". However, whenever possible, I prefer a first-time reading or viewing or listening experience to be uncluttered with too much advance knowledge. There can only be one "first-time experience" and I prefer not to have it "spoiled".
Subsequent viewings, readings and listening sessions offer me a way to appreciate different aspects of a particular work (assuming it warrants subsequent visits) but I still want a fresh version the first time out.
The Sixth Sense, for example, is something I would probably have not enjoyed nearly as much as I did the first time I saw it if the "reveal" had been known to me beforehand. I enjoyed it a second time, but in large part, that was owing to watching my wife watching it for the first time and seeing her reactions to various elements of the film (as well as wondering if she would figure out the "reveal" ahead of time). I also was interested to see if there were any glaring errors that should have alerted me to the "reveal" the first time through--I found nothing in particular. I was able to spot the clues, being in on the reveal, but they were skillfully and subtly presented.
I don't begrudge anyone who wants to be spoiled for this movie (or any other) but there is merit in a first-time "unspoiled" experience that makes me resist major spoilers.