In my experience, online courses tend to be a bit more work than on-campus courses. For example, I took one American Lit course online, and since we did not have the opportunity for in-class discussion, we had to write an essay each week about the assigned readings, post it online, then post analysis of other students' essays. (This was in addition to the usual lit papers and tests.) I didn't mind it because I like to write, but for some students it was kind of overwhelming.
I've never taken a course that incorporated scheduled chats, but friends who have say those chats are much less conducive to useful conversation than are the message board discussions.
I agree with the others who said you have to be self-motivated to keep up with online courses. It's VERY easy to let yourself slack off when you don't have to go to class. But for a lot of people, myself included, online courses can give you the flexibility you need to get your coursework done and still meet your other obligations.
I will say though that sometimes taking on-campus courses can have some benefits too. I went back to school as an adult with 3 young children. I had a professor my first semester who I formed a great relationship with, and she instilled tremendous confidence in me to keep going and finish my degree. That's the kind of thing you really can't get through online courses.