The last film in original series - Battle for the Planet of the Apes - ends the series as the weakest of the saga. Ten years since Caesar led his uprising - humans are now enslaved by Apes. Earth has seemingly been flattened by a nuclear bomb and only a small human community - bitter and deformed by the ravages of the blast - continue to exist beneath the rubble in an underground bunker. This group would later evolve into the Telekinetic race seen in Beneath the Planet of the Apes.
The main fault of the film is the low-budget look. Every successive film in the series had a reduced budget from the previous and in Battle this really shows. The majority of the film looks as if it were filmed in someones back-garden, the same costumes are used from all the films previous, the script isn't great and the hokey actions scenes detract from the visual experience of the film. Battle at least remains true to the series overall seriousness and doesn't assume its audience has gotten less willing to engage with serious themes over the years, this isn't Star Trek V: The Final Frontier...
The film tries to explore the uneasy tension as the Apes try to live in peace with a now enslaved human race but this never quite hits any high notes. One of the films main antagonists is Aldo - a war-mongering, human-hating gorilla who is vying for power with Caesar. In Escape from the Planet of the Apes, it is mentioned that an ape named Aldo would be the first to speak and rise against the human race but Caesar's rise instead means that Aldo is now second-tier. Not that he knows this, but for continuations sake, Battle tinkers with original timeline and presents a possible future under the doctrines of Caesar which is more upbeat and hopeful to the one we see in Planet of Apes.
There are much worse science fiction films out there, and with bigger budgets than Battle. The most admirable thing about the Apes series is even after 4 sequels the series remained reasonably strong. How many science-fiction franchises can that be applied to. The most 'epic' and venerated - Star Wars, became a poor imitation of itself beginning with The Phantom Menace, The less said of all The Matrix sequels the better. Terminator? Godzilla? Jaws? Jurassic Park? The list could go on.
That's it for Apes! As you can probably tell, I really enjoy this series. Despite all the flaws, there's much to admire. I may include a bonus Rise of the Planet of the Apes post when I get round to watching it. I've heard it's a great effort.