I have a large collection of physical books which I'm still trying to get through (I estimate I have a 2-3 year backlog based on my typical reading behavior). I have both a Nook and an iPad with e-reader apps. I've downloaded many public domain books to the e-readers, but haven't gotten through them yet.
When people see the stacks of books I own, they say I should just get an e-reader. Of course I tell them I already own one, but that not everything I want to read is available in e-format, and that there are still advantages to owning non-volatile storage media.