Unfortunately, I never saw this movie as a kid. I would have loved it. But seeing it for the first time in my twenties, despite some bad acting and cheesy dialogue, the film was thoroughly enjoyable. The visual graphics in the film are amazing. The colors and otherworldliness really take you into another place.
Not only is the film completely over the top, it's actually a pretty decent take on totalitarianism and the nature of dictators. By inspiring fear into the hearts of his subjects, Ming is able to "divide and conquer". The people are so afraid of Ming that they will sell each other out for his favor. But Flash Gordon, through his conscience and humanity, is able to bring them together to topple the psychopathic Ming.
Oh, and the Queen soundtrack is worth the price alone.