It's possible to summarise the premise of The Rainbow Thief more succinctly than the vast majority of Alejandro Jodorowsky films, but make no mistake: it's oftentimes just as baffling to watch as his more notorious films.
Maybe this is as a result of watching it after Jodorowsky's frustrating 2019 documentary Psychomagic, but I found The Rainbow Thief alright. It's appealing as a bizarre burst of incomprehensible energy that doesn't overstay its welcome, at only about 90 minutes long. It's also a chance to see some well-known actors getting on in years (Peter O'Toole, Omar Shariff, and even Christopher Lee for a bit) cut loose and have what looks like fun on screen.
That distinctive Jodorowsky atmosphere plus the strong cast make The Rainbow Thief watchable... still probably not essential, but worth digging out for fans of the filmmaker's work.