I use to watch this show when it was on (when I was a kid). That tells you how old I am I guess. Anyway, the show was pretty good at the time but doesn't real hold up against current day comedies.
Penny Marshall (now a famous movie director) starred as Laverne DeFazio along with Cindy Wiiliams as Shirley Wilhelmina Feeney. Both were pretty good at their roles. There were several other actors that made it big after the show. Ed Marinaro who later went on to star in Hill Street Blues joined the cast in season six. Michael McKean who played Lenny Kosnowski has gone on to make several movies.