George,
You hit on three very important words in your response immediately: prompt, rubrics, and specific. With appropriate rubrics, it is easy also to provide consistent feedback.
You are correct in that the rubric must be easy to understand from the student's point of view, yet comprehensive enough to be a substantial grading too. I also put my learning objectives in the rubric so that students can see how the objectives of the course relate to specific assignments/projects.
Thanks for your input.
