THANK GOD IT'S FRIDAY was released just as the disco craze crested, when anything and everything might happen during a night on the town, when sex was casual, and drink and drugs were still regarded in a lighthearted manner, and music wailed and blared with the likes of Gloria Gaynor and K.C. & the Sunshine Band. Within a few years Disco would be publically declared dead--but it still lives on in the recordings... and in Donna Summer's penultimate screen image of the Disco Diva, shimmering in the spotlight beneath the mirror ball with a hibiscus tucked into her hair as she belts out her megaton hit, "Last Dance."But then Donna Summer steps into the spotlight--and for a few moments everything that was magic about Disco lives and breathes again. For what it is--an incredibly light, mindless bit of tinsel--the film is well done, but it has an extremely limited appeal for a contemporary audience. Unless you were actually part of the disco scene and want to revisit old memories, you're better off catching it on the late-late show. But my oh my...