It depends on the person, also the material of course. For me, I'll use RPO as an example, Cline paints enough of a picture for me (with my own nostalgia and affinity for the stuff in this book as well for the 80's and 70's sci-fi and pop culture), I found myself fully immersed and able to visualize what he was trying to picture for the readers. Every time I opened that book, I was in the Oasis with Parzival, looking for the Keys, etc. The explosion of the Stacks, I felt like I was with him in the van and felt the shaking from the explosion as well, I got goosebumps reading that book.
I didn't when I saw the trailer for it. Movies and tv shows leave a lot out, some stuff just can not be adapted well enough or it just doesn't make sense with the time you are allotted. So for me, yeah the movies and tv shows are cool for adaptations, but I still find the time to read the books, because that's what the author intended you to see first, some do help adapt it to screen play, but not all do and in doing so, a lot of the emotion of the original material is taken away I find.
Which is not to say I do not enjoy the adaptations to film or tv, I just have to really force myself to realize that they are not straight adaptations.