Update: Karen below corrects me: yes, you can indeed return books on the Kindle, within seven days (as opposed to 30). You have to contact customer support, however—it’s not an automated system as with other Amazon products. Karen also comments below that there’s a rebate program if you buy the book from Books on Board for Breaking Dawn.
At least with a real book ordered online, you have some hope of canceling your order or just shipping the book back unread (of course, it’s likely that even then, desire will have you ripping open the packaging anyways).
With a digital edition, not only is it already there on your Kindle or eReader, but you can’t return it (just like you can’t return books at a bookstore).
Case in point, Stephenie Meyer’s Breaking Dawn. I hope I’m in time to save you from it, but I fear I may not be.
See the hilarious and frighteningly true recaps from cleolinda here:
They’re actually a great replacement for the book.
(No, I didn’t buy Breaking Dawn in any form, but I feel a bit sorry for those who did and weren’t expecting this.)