I can see where pictures and "extra" might do well for kids book or for books read on an ebook reader with a larger and more spectacular screen (like we keep hoping to see from a new display technology sometime).
I can also think of a handful of books that were non-fiction stories that had a few pictures so you could see the real event and the real people involved. That would be nice.
But for almost all the books I read, all I want is the text, and it's an uneccessary but pleasant bonus to get some formatting to make headings/chapter breaks clear, some formatting for italics and bold if necessary, and maybe even some hyperlinks if the material suggests it.
Basically I guess I'm with rlauzon... text only is just fine. Why does a novel need pictures?