I've been using Fritz 16 this week. My only issue so far has been that sometimes the kibitzer will blank out.
I prefer the interface of 16 over 15, it feels cleaner. I need to use it much more though before I could give a more detailed review but at the moment I don't really see THAT much of a difference from Fritz 15, so whether it is worth getting if you already have 15 is hard to call. If you have 15 maybe wait for a sale (I got it with the 25% launch discount).
..Fritz it has negative enrgy or waves and it belongs to German school of chess! that is a school of magic(absurd or desire to win only) and has nothing to do with memory chess(european chess) or thinking chess(american chess)!
naturally it has been left alone by people after tasting its power really. it is like Crafty but more aggressive at inducing its black ideas!
Through Fritz 13, the engine was a product of Frans Morsch and Mathias Feist (Germany). Fritz 14 (updated Pandix engine) was by Gyula Horvath (Hungary). Fritz 15 and 16 were by Vasik Rajlich (Czech-American). You can think of Fritz 15 and 16 as updated or tweaked versions of Rybka.