“Margaret Garner turns out to be an honorable achievement, if one that is often reluctant to seize the story’s tragic elements by the neck and render them shocking. Danielpour’s relentlessly lyrical score, though marked by episodes of limpid beauty, lacks dramatic momentum and contrast, with long, lethargic stretches that stop the opera in its tracks. Morrison may be a stranger to the medium, but she is familiar with the story on which she has weaved operatic variations.”