This might be enjoyed best as a review of 40-year old television effort. Gene Roddenberry is best remembered for Star Trek, but this Air Force veteran was writing well before the 1966 show hit the airwaves.
"Planet Earth" can be enjoyed on its own, but I got the opportunity to watch "Genesis II" first. Both these television pilots are based on the same story of a scientist suspended in time for 160 years. The world has mostly destroyed itself and we're invited for a collection of never-to-appear stories of the survivors bringing mankind back.
This story premise and those from Star Trek pivot on some type of Third World War wiping about most of our civilization. While Star Trek plots all seems to share the idea that mankind has evolved into a better kind of person, Planet Earth did not display that sensation to me; and maybe that's the problem. The illusion of an improved man seemed to led the following of Trekkers, plus the boundless story opportunities of visiting other planets. There was no way to expect that sense of wonderness with this story. Even though this future is probably a truer presentation of mankind following such a war, people like illusions and the lies to make us feel better.
Also interesting to see is the kind of loyalty Roddenberry has with actors. Like using DeForest Kelley, Leonard Nimoy, Nichelle Nichols and Majel Barrett (who he later married) on previous projects and then including them in Star Trek, Planet Earth cast includes Star Trek Alumni Diana Muldaur, Ted Cassidy and of course Majel.
I don't recall seeing either of the pilots (Genesis II or Planet Earth) in 1974 but I'm fairly sure I wouldn't been very intrigued by them. Roddenberry's humanists views are quite evident in all his material, which can make it difficult to fully engage in his stories. Star Trek, for the most part, worked well -- Planet Earth didn't. John Saxon acting and fight-scenes are better in other productions. Diana Muldaur is a very strong actress with great presence, but her character here was tiresome and I just wanted her to go away. I was looking forward to anything interesting for Ted Cassidy, but we barely see him.
So if you're interested in shows from the 70s or in Roddenberry, watch Planet Earth and possible Genesis II, but don't be disappointed that a new story franchise was not born.