This isn't really an overlooked movie, but have you seen it? Or have you seen it lately? The reason I can't call it overlooked is because it inspired so many unofficial sequels, ripoffs, remakes, and homages that nobody seems to know how many of them there are. I've seen estimates ranging from 30 to 100. And of course Tarantino's Django Unchained drew a lot of attention a few years ago. Franco Nero, the original Django, had a cameo in that one.
I think the movie's beyond criticism. It's the kind of thing where the only street in the ghost town that's the setting for most of it is a loblolly, even though it never rains, and everything beyond the ghost town looks like Death Valley. There's a weird religious sect run by a man who likes to kill people for sport. There's a lot of gold, and there's a force of Mexicans equal to the force of the religious sect. Django is out for revenge on the leader of the sect, and like Clint Eastwood, he plays the Mexicans against the sect. Many people die. Hundreds, would be my guess. It didn't really make a lot of sense to me, but what the heck. I enjoyed it quite a bit, anyway. Because -- quicksand! You cannot go wrong with lots of shooting and fighting and quicksand. It's not really the plot that matters in movies like this. It's the choreographed gunplay, the little touches with the main character, the soundtrack (this has a good one), and other things that keep me watching.
Django is regarded as a classic spaghetti western. If you like those films, this is one you have to see. If you don't like them, this probably won't convert you.