Yes, it is a game worth playing, but not perfect.
It already has an impressive array of cars (imagine the growth of the roster in GT7) each with impeccable detail and sounds. Physics are arguably the best in any GT game (GT6 was too grippy; while GT4 was understeer hell). The Livery Editor is a GODSEND - you basically have limitless options and even have the capability to upload your own decals! And as well as being able to share your creativity. Photo Mode has vastly improved, with numerous filters to play with, and personally this saves me a lot of time editing the photos in the Photoshop. Porsche is a very welcome addition, and I'm always in utopia whenever I drive the 911s in the game.
Now, what are the faults?
The BoP and class system could seriously use a lot of tweaking. Thankfully GT7 will have Performance Points back. My main beef with balancing is that there are cars that are overwhelmingly dominant on certain tracks, and did not use the real-life BoP based on the circuit - a prevailing issue among the Group 3 class. N Class is a nightmare, mainly because there are certain cars that tend to dominate over others despite the BoP (I'm talking to you, 911 GT3 RS and GT40). Group 4 is the lesser evil.
Verdict? Well, it started out with a few problems, but time passed by and it blossomed into greatness.