Despite some funny moments and interesting ideas (the snake-hand of the tribe leader, for example), this was a pretty dreadful film that even "stoners" would be reluctant to embrace. Everything was tepid, bland, and uninspired - which is a shame, because David Gordon Green has always been so inventive. Oh, wait...
The jokes are funny, but the idea of parodying 80's sword and sorcery movies is icing on icing- the films they specifically parody ("The Sword and The Sorcereor", "Krull", "Conan The Barbarian") were already pretty ridiculous as it was. The McBride character's "arc" was weak, so his "redemption" doesn't work at all. Genre spoofing has been so elevated by Simon Pegg, that anything else seems pretty tired.
YOUR HIGHNESS is an incredibly lazy piece of filmmaking, even for a stoner movie. It gets off a few chickles here and there, but evaporates as you're watching it. Nothing memorable about it, aside from how much it misses its "Cheech & Chong's Princess Bride" target.
It's not just that it's awful, it's that it's SO awful that I honestly cannot figure out just HOW it can be so awful. Didn't somebody at some point turn to David Gordon Green and ask, "Are you sure this is what you want, mate?"