I am interested in identifying a writing assessment service that provides students with instant feedback for a variety of writing modes and that offers a range of feedback/assessment. I also want the capability for teachers to customize the assignments and assessments, and add their own written notes to student-generated papers.
Our English department is looking at the Criterion program. It sounds like it does what you are looking for. However, there are no free demos available, only webinars that you have to sign up for. Since the first webinar didn't work for people who were outside of the U.S., I can't provide you with any feedback about how good the program actually is.
Writing Revisor from SAS in Schools is free. You can try the demo.
or subscribe for the full service. It does not give you a holistic score, but offers guiding lessons and revision tool.