I've made a donation, so I feel I can share with legitimacy. And, my rating is 5 stars. First, you need this plug-in. I couldn't live without it.
However, like all of Yoast's plugins, documentation is light, and overlap causes ambiguity. It's a challenge to set up. Even the best webmasters I know say they get confused.
Too many questions go unanswered in the forums. EASY to fix, though - just build the network of followers willing to do support (there are plenty of users, shouldn't be hard to do), share a little of the pie with them on an per-answered support thread. PageLines (drag and drop theme) has built a great support network (real time, chat) that way. Would love to see that sort of thing from Yoast.
All In all, I give it 5 stars, just want to be more than a numbered user in the community. ;-]