almost all waking hours. check email and news in bed in morning. watch tv / read a book over breakfast. have it on all day next to my computer displaying materials for my research. read it in bed before going to sleep.
before i got the ipad i tried (with some success) to use the kindle dx, and often ended up lugging around books as well. but, now i am totally book free. what a difference!
without the pdfs, i'd probably never use the ipad at all. so, if people are not using it as a reader, i am not sure how they could get much use out of it.