I have taught the same course online since Spring 2000, during summer session since 2001, on campus during the evening since 2002 and daytime since 2003.
The class is half over, and I just sent out feedback to all students to give them a pat on the back - or a wake up call. Honestly, the round of emailing that usually follows the feedback can be frustrating. Do students think they can do nothing and get a good grade? Or even pass the course? I just yelled at my screen, "how about this for an idea? Put in some (censored) effort!"
Online learning is not everyone's cup of tea. Independent, self-directed learners prefer it, it makes life easier for those with difficult schedules or who live a distance from campus, and students who are shy about speaking in front of others often find their voice via electronic discussion. Discussion is always very good in the online class; on campus, the quality varies. A lot. On the other hand, students who like the immediacy of the classroom, the nuances of body language, the reminders, pointers and reassurances about assignments, miss the classroom.
In my experience, the range of students in the online version of the class is very wide. During summer session, the students tend to be very strong, for the most part. I speculate that students who attend classes in the summer are among the best students in the university - whether on campus or online. However, during both the academic year and in the summer (when I always get a few students who are taking the class solely because they failed something in their college career, and need something, anything, to graduate - they are always either extremely motivated because they have learned a hard lesson, or more often just plain awful because they simply want to be done) it is in the online class where I have found both the strongest, and the weakest students. The strongest students make my job very easy, they bring so much insight and energy to every topic. I wonder about the weak students, if perhaps they expected the class to be a piece of cake, for some reason do not drop it when the unpleasant reality sets in, and instead are not making much effort, or if they are just in over their heads with the online format - or if they are weak students in general, and are aiming for a D-.
One other drawback that I have found over the years is that plagiarism has been more common in the online section. It isn't completely absent on campus either, sadly. Whether cheating is something that has always existed to the degree I have encountered it, or if it has been facilitated by the Internet, or a lack of absolutes in terms of morality and ethics in modern society, or the focus on getting a piece of paper and a job rather than learning, or careless professors who do not check or let offending students get away with a light penalty, I do not know. But in the 15 or so times I have discovered plagiarized essays, 75% of them have been in the online class. There was one incident in the online class last semester, in fact. Perhaps the anonymous nature makes it more tempting, perhaps the stern nature of my remarks to the class in the opening lecture on campus are taken more seriously, perhaps being online so much with the seductive cheathouse.com and other such vendors just a few clicks away makes it easier?
I'll end with something positive. I have not detected any cheating during summer session this year (yet?).