I'm in an interesting position these days - I'm a distance learner on an MA course that utilises VLEs and I teach English courses which are face to face and also make use of Blackboard Vista as a learning content management system. So I'm getting to look at VLEs from the viewpoint of both educator and student.
As a student and as a teacher the clear advantage of the VLE is knowing that it's a one stop-shop for everything you need to know about the course. It's very reassuring for the geographically distant student (once you've got the hang of the tools and navigation). It's especially handy when you're not in sync with the other course participants who attend face to face classes so you can catch up, read ahead and so on without having to check in with the course leader all the time. The students that I teach also enjoy being able to repeat learning tasks on the VLE until they get 100%; it has helped their language accuracy enormously and they have been able repeat tasks at their own pace.
However, this independence does have its drawbacks. For example, as a distance learner it's very easy to get behind with work if you're not being chivvied along; BBV can tend to be writing based which means a lot of extra reading is needed as well as background academic articles. I tend to print out course materials to read when I have the chance. Also reading from a page reduces the eye strain that I'm experiencing these days due largely to the amount of back-lit screen reading we teachers do, as well as having data-projectors facing us at the front of the classroom. I worry as well that educators could over-rely on the VLE as a method of gathering evidence about the student's engagement in the course judging participation and understanding too much by tracking of how much access students have made of the VLE and their volume of postings.
So, I think that a big drawback of a VLE in comparison to F2F teaching is that the VLE cannot tell us the non-verbal and/or unwritten interactions that take place in a classroom setting. As teachers we get so much information about our students' individual needs by observing their responses to class tasks and their peers - this is certainly the case in the field of language teaching. There's also the pastoral element of being a teacher to consider as well. In a F2F setting we can easily see if students are losing motivation, having difficulties or needing additional support.
As well as this, it's so much more time-consuming to write one's opinions down in an accessible way than it is to verbalise them to a group in class. However that in itself could be seen as a benefit: the need to present opinions in a publishable form hones your academic writing skills.
