I've just finished my ATPL ground theory with HubAir.
The course material is very good (Bristol). Follow-up (progress tests) are done via a tool installed on the pc (it's also from Bristol).
After you've finished module A or B, you have to follow a one week revision course (one week per module). The revision courses are not really lectures, but are more a question and answer seminar. All in all, I'm very happy with their course and support.