Any digital media is worth a plug
People who use technology will be people who go on line....MILLIONS OF THEM!
I have sold quite a few through Facebook, many to friends of friends of friends...the new way to pass it on. If you learn how to use FB correctly and use of security settings or simply block nob heads it is a great media. But there are many other sites of a similar function.
As for reviews on sites selling your book...don't trust them. I had many on Amazon, they have now gone for no reason other than some tech adjustment at amazon losing or forgetting to restore reviews. The only way to promote is to tell people about it in any and every way possible so it might just help if you go to the trouble of telling us your plan is to tell us about your book too. Good idea do you think?