Pros
They have a relatively large number of leads compared to other companies I've worked with in the DC Metro area. They aggressively recruit you for new clients and new jobs, so this works out well if you're looking for hours. They are always nice and professional, and clearly care about doing their jobs well.
Cons
A few times I received my check a bit late in the mail. I didn't consider it a major hassle, but it was noticeable. Also, if you're able to work directly with a client, it may get you a better deal. Novastar Prep, like any other tutoring company, will take a healthy percentage out of what the client pays per hour. However, it may be worth it in terms of them finding and pursuing leads, and handling the payroll and admin tasks, depending on your own perspective.