UPDATE: The free factory content is right there with the player download:
http://www.native-instruments.com/#/en/products/producer/kontakt-5-player/?page=2483 ~~~
NI offers some free content for the free player. In the free content are good basses, a good rhodes, a clav, a solid drum kit, and quite a few other things.
Sorry I can't find the link for the free stuff, but I posted it on another thread. If you crawl NI's site you will it.
A lot of good libraries (like Vir 2) use the free player.
Re: the full player:
I just cross-graded to the full Kontakt 5 and got the full sample content (1,000+ insturments). It is great but didn't do much for me since I already had Vienna, Hollywood, Ivory 2, RealGuitar, RealStrat, RealLPC, Acoustic Legends, Electri6ity, and other stuff. However, if you don't have a big sample library, the full Kontakt 5 is a great deal.