taralazar, thanks for sharing this - really interesting.
I'm struggling to visualise what it will be like. If it's very pinterest-y - just sharing cover+blurb+a few words of a review, for instance - I can't imagine wanting to use it, because I love reading long & thoughtful reviews. Thorough reviews also help me decide whether that reviewer has similar tastes to mine, and will I follow them & take their recommendations regularly. I do love pinterest for specific uses (e.g. inspiration image boards for WIPs) but can't STAND the options of browsing everything tagged "art" or "history" or whatever, because half the userbase of pinterest seems to have no idea how to use them... A quick glance just now at the "history" category shows 2 recipes, a kid's costume how-to, a religious quote, a motivational quote, five pictures of vintage clothes, one top-20-beauty-tips, a guide on how to use a flat iron ... The idea of a book website like that depresses me.
And if it's very goodreads-y? - well, as someone else said upthread, why bother switching websites?? I don't think goodreads is perfect, but it's functional, established & has a big userbase. Unless Riffle offers something staggeringly innovative, I don't know to what extent people would migrate.
And if it's a mashup ... it COULD be good. But it also could go really wrong.
All that said, of course I've signed up to request an invite