Let's set aside, for the moment, the huge miss Apple, Sony and Kobo made in not buying Goodreads if for no other reason that book reviews are scarce on those ebook sites apart from bestseller books. The two nagging questions I have relate to Google Books (now called Google Play) and the different review systems on Amazon and Goodreads.
Reviews on Google Books are populated by reviews on Goodreads. Expect this to end shortly. Did Google not go after Goodreads because it felt there was no need given the automatic porting of reviews? Wow.
What's of greater long term interest is that reviews are posted differently on Amazon and Goodreads. Currently on Amazon, the review with the highest number of likes (minus dislikes) sits in the top review spot. On Goodreads, the latest review gets top billing regardless of the number of likes. Watch for this to change. I also expect Goodreads will be adding a dislike button to its reviews in the near future. Here we go.