I can definitely see how many who may go back & watch the first would think it is not good. It was a low budget movie with a weird premise & a bunch of no-name Aussie's acting in it. At the time, though, it had a very different feel to it and it was weird and creepy, especially the villain, Toecutter. Hugh Keays-Byrne was the actor who portrayed Toecutter, and it just so happens he plays the part of Immortan Joe in Fury Road. Dude's come full circle
Anyways, Mad Max set up the Road Warrior, which was friggin' awesome & holds up a lot better (Can't believe that was 1981!). The third had its good moments but imo it could have done without the whole group of kids/Lord of the Flies in the desert thing which was too far out there. As long as Fury Road & any other continuations of this series stay away from that sort of thing will be the way to go.
Crazy thinking George Miller's work as a director is limited as it is & goes from the Mad Max franchise to the Witches of Eastwick, then Babe Pig in the City and then the two Happy Feet installments, then now back to Max. Seems he's still got it though with Fury Road, to which I'm very happy.