On mine (Beneath The Shining Mountains) I started with the title, which isn't as odd as it sounds. If the backcover shows up on Amazon where else might it? If the author's name isn't on it, the title better be or how is the book going to be found?
I then added a very short clip from a review, ie 3 words, choosing a group of power words, then the blurb, then finished with a couple more review clips in italics.
It's not so much a case of less is less or more is better, it is the *space* that matters. Would you want to read a backcover that is one solid edge-to-edge text from top to barcode?
I like Edward Grant's suggestion of a QR code, and will bear that in mind for my own.