Ersatz, saccharine, treacly: these words aptly -- and predictably -- describe Brown Sugar. Dre (Taye Diggs) and Sidney (Sanaa Lathan) are childhood friends whose love of hip-hop lies behind their successful careers: he's a record producer, she's a writer. Sidney moves back to NYC from LA to finish her book (a hip-hop memoir) and helm a music mag; Dre quits his high-profile job to start his own label and promote a cab-driving rapper (an understated and hilarious Mos Def). Dre is planning to marry a glamorous lawyer (Nicole Ari Parker) and Sid is dating a charming Knicks star (Boris Kodjoe), but you know they're in love with each other, in a Harry-and-Sally kinda way. They mark time with white wine and kickboxing classes. Queen Latifah keeps it real as Sid's matchmaking cousin, and director Rick Famuyiwa (The Wood) gets it right with docu-style commentary from musical artists of then and now (De La Soul, Method Man). The soundtrack is also fine, including Cassandra Wilson's dark retelling of Cyndi Lauper's "Time After Time." But the clichés mount up in cloying layers until Brown Sugar leaves a sour taste. (108 minutes) At the Entertainment, Flagship, Holiday, Providence Place 16, and Showcase cinemas.