In the context of what this is it's 4 stars. Cult Classic
I mean by any individual measure this is a 2 star work.
However this was released in 1980, and to those exposed to D&D this was pretty cool cringe worthy story in all. Everything about this is bad on so many levels but look what was made at that time. Yes this movie is pure cheese but like some funky aged cheeses it's so bad it's good.
I view this in a similar way to the old Hitch Hikers guide TV series.