Houston's performance proves that this could have been the first step not merely in a comeback but in a major re-invention. She had the instincts of a superb character actress.
If the film is a sudsy show-business Cinderella story in which Emma's youngest daughter, Sparkle (Jordin Sparks), ascends to glory, Houston's presence makes it a cautionary tale.
The forebear's underwritten melodrama has been supplanted by Tyler Perry-like soap operatics and much jawing about the Lord, riots in the Motor City, marriage proposals, and maternal heartbreak and disapproval.
Sparkle deals in such well-worn rise-and-fall music-bio tropes that it's hard to blame it for simply coasting on narrative shorthand at times. But the lackadaisical storytelling can inch toward outright laziness.