The 4k set is a six-disc set containing two UHD discs and four regular Blu-Ray discs. It includes the theatrical version of the film, which is about 2.5 hours long, the Redux cut, which is about 3 hours and 16 minutes long, and the Final cut, which is just over 3 hours long. Each version is both on a UHD disc and a regular Blu-ray. There are a ton of extras, some of which are new, and some which are carried over from prior DVD releases of the movie, including a discussion between Martin Sheen and Coppola, which was done in 2010 for a prior release, a 1936 radio broadcast of Heart of Darkness (which was a huge inspiration for the movie) narrated by Orson Wells, deleted scenes, and much more. There is also a commentary track by Coppola on the Redux version of the movie, which gives a lot of insight into the process of making the movie, including how George Lucas was supposed to direct it before he started making Star Wars and how Coppola made a lot of it up as he was shooting the movie, and was not working off a finished script.
It is definitely not a movie that everyone will like. But if you are a fan of the movie, the actors, and/or the director and especially love when a lot of bonus material is available, it looks and sounds great. And you get every possible variation of the movie that will ever be put out. It is a must-get, even if you have one of the earlier releases.