Robin Solsjö Höglund’s review published on Letterboxd:
Finally, the third and final viewing. This time the longest Redux cut, my preferred way to watch. Yes, you could argue that the additions technically don't add much - the hookup with the Playboy Bunnies, the longer French Plantation sequence and the scene of Kurtz reading to Willard from Time Magazine, in broad daylight, which kind of demystifies him. But if you're going to watch it, why not go all the way?
Compared to the Theatrical Cut it's quite different, but compared to The Final Cut the only three significant changes are the ones I just listed. It's only about 16 minutes longer. But again, I like to soak in it. And now I'm all Apocalypsed out for some time.
If you're watching the film for the very first time, I'd go Theatrical. You get the jist of it. If you want something special, Redux. If you find Redux a tad too long, The Final Cut.