Do the benefits of scripted curricula outweigh the drawbacks?

The U.S. Department of Education was criticized recently for endorsing specific products and curricula for its Reading First initiative, a program established under the No Child Left Behind Act. Some of these curricula are very prescriptive, delineating every aspect of the lesson described -- even the instructor’s own words and gestures. Still, these methods are supported by scientific research, and having this kind of proven uniformity in classrooms might help schools achieve high educational standards. What do you think?