Making a movie out of the 50s sitcom and substituting black characters half a century later sounds like a dubious proposition on multiple levels. But thanks to some affectionate fidelity to the original characters, plus a spirited castCedric the Entertainer and Gabrielle Union as Ralph and Alice Kramden, Mike Epps as Ed Nortonthis plays a bit better than it sounds. I miss the show’s mangy, minimalist sets, but the slapdash narrative construction and good-hearted schmaltz survive intact. With Regina Hall and extra mugging from John Leguizamo and Jon Polito. PG-13, 90 min. (JR)