I found installing the Free Kontakt player to be very useful. Firstly the factory sounds are fine and offer some quite useful patches.
The main reason though is that I have a host of other full version synths from Native Instruments themselves that need the free player in order to run. That makes it reason alone to install it. It means you don't have to buy the full version of Kontakt in order to use may full versions of other Native synths.
Then there are third party synths to which there are many that offer full versions but also run in the free Kontakt player.
(there are also plenty that also need the full version of Kontakt to run as well) It depends on your needs but if it involves using either Native synths or other synths then it is a
very worthwhile install to do.