Some online ones are really easy, some requires more work. I have two friends who did an online one and they completely hated it because the lecturer in charge was not very nice and amrked really harshly.
I did the Energy and Mineral Resources one and I quite enjoyed it. The only thing was you have to contribute to online discussion and there are so many posts to keep track of you people repeat the same thing over and over again - I'm not sure how well these people score with their participation marks.
The assessment tasks were one essay, online participation, group work, and 2 quizzes.