Follow up picks up somewhat implausibly from the previous left off. Same sets but lack of new ideas sunk pic. Made a little cheaper judging by the number of substandard masks used. By the time we make it to the "mutants" one really has stopped caring. Good end though with an epic body count. Has it moments but not enough of them, the the timely political allusions just silly.
I love this movie way more than I ought to. It's barely an apes film at all - it's practically the first film, with psychic mutants as the enemies instead of apes. It's more like one of those off-the-wall 1970s apocalypse movies like Glen and Randa or A Boy and his Dog than a sequel to Planet.