As a classroom teacher I found once I learned how to use one feature such as running the reports, other activities such as assigning work was easy to do.

Because they don't care and they are getting paid no matter what.

As a teacher I have found very few issues. The biggest challenge is when a student is uploading an assignment that is not automatically graded. All my students also have my email so they just email me a copy of the assignment then I give them full credit. The work around issues is best done through the teachers.