While acknowledging that we can’t judge books by their covers, how much does the design of a book affect your reading enjoyment? Hardcover vs. softcover? Trade paperback vs. mass market paperback? Font? Illustrations? Etc.?
If I don't know anything about a book, I do judge it by its cover. If the cover is interesting, I'll pick it up and read the book. I judge them by titles too though, so if the cover is horrible but the title sounds interesting, I'll also pick it up.
But none of these things influence my enjoyment of the book itself. I won't buy a book if the font is tiny, I'll look for another edition if I really want it though. I don't mind if it's a paperback of hardcover - I buy mostly paperbacks, but most of the books at the local library are hardcover so I read both. I don't mind if it has illustrations or not - except for history books. I prefer history-related books that have maps and illustrations, otherwise it can be quite difficult to visualise what's happenening.
As long as it looks like a book I'll read it - I don't enjoy reading things printed off the internet and such, but as far as books go I'm pretty easy!