It's sensationalist for sure and not a good documentary per se (I'm not sure Sperlock ever made a good one) but I enjoyed it as an exploitative horror movie more than anything else. I'm fairly rat phobic so it worked for me.
A more profoundly, confoundingly, relentlessly odd film you're unlikely to encounter. Too creepy for kids, too baffling for adults. I've got no idea what Altman was trying to achieve but it's fascinating. I'm a couple of rewatches away from declaring it a work of crazed genius.