PlayerIO is certenly a great tool for multiplayer develop because the its very easy to use (the basics) , have easy access to databases without needing mysql or similars, they host your server, etc its really a good service and i use it in some games of my own, the bad thing is that there is some lack of documentation, the uinity example you provide is not really enought to have an overall idea of how to do many things like turn based games, fps, mmo. this makes harder to us developers to grow. by example i havent been able to make a character move using the keyboard and i cant find any info regarding.
I really like playerIO and i wish there were more documentation, examples and comunity support for unity. if i can help somehow to make playerIO better please let me know.