I just saw the film for the first time tonight, so these are some brief impressions.
This virtually unknown little movie is a weird, goofy, silly, and touchingly sincere experience. The very premise of the film is fascinating, and though we've seen the "old-time hero in the modern world" premise before and since, this is one effort that really delves into the potential of that idea. The script keeps dropping in bits of social satire and commentary; the evil villain's plot is essentially the inverse of "white flight", seeking to "purify" New York by luring all the minorities to the suburbs and then killing them. The implication that he's also the supreme evil force in the universe adds a neat mythic touch. The Captain's quest to re- capture the spirit of America that inspired him to begin with is rather sweet, and Kate Fitzpatrick is charming as the spunky heroine. (Arkin and Lee are great, but aren't they always.) The songs are generally fun, even when predictable- despite being written by a number of different people (including Richard O' Brien!) they've got a nice consistency.
It's a flawed film in many ways- the humor is uneven, ranging from the clever to the silly (often at the same time- though "Amazing Computer Brain is Stuck!" got a laugh from me.) The finale is so abbreviated that I'm convinced there were scenes that were either cut or never filmed. And, this isn't really a criticism, but I do wonder why Australians were making a movie about the American spirit.
Still, this movie doesn't deserve the sheer obscurity it seems to suffer. It's undoubtedly a unique film, and as such provides a truly fascinating experience.