Some of the acting may be less than great (ahem) but this film is just so much fun to watch! Lucas created a complete universe that is easy for the audience to believe in and become part of. Also, he stuck with one of the oldest story/myth progressions of all time, which I think is why the film works so well and is so enjoyable (that goes for the whole trilogy, really). Even the SFX looked better than sci-fi films that followed for the next 15 years until CGI really hit its stride. And who didn't want to be Hans Solo when they were young (boys, anyway) because he had the coolest ship and sidekick in the galaxy...