You're right TheNlightenedOne--it was amazingly aawesome. I have it installed on both my 650 and my 350. It just makes the reader so much better! One of my favorite features is the clock in the bottom right of the screen.
And I know there have been a few reports of batteries quickly draining after installing PRS+. Luckily this didn't happen to either of my readers, but it did to a friend's reader. And just for the record, she was able to uninstall PRS+ and go back to factory settings without any problems.