In reply to SouthernSteve:
It is inevitable that completion rates for MOOCs will be low given that anyone can start one and you can start without paying, as I normally do, and even if you do pay, the cost is often low.
MOOCs probably don't work that well for weak and unmotivated learners. But if you are motivated and disciplined and you choose the right MOOC, they can be a great way to learn.
I only worry about what I am going to learn and not about how what I have done will be regarded by an employer, nor about the gaining of transferable credits. Others might need to do that. If you need an actual masters, then you need to do one.
I must say that by the time I need to pay I normally have a very good idea as to whether doing so will be worth it for me. By that time, if at all in fact, the fraction of other learners who complete is not something I consider. I do consider whether the course seems to be of high enough quality so that the time and money required will be well spent. The experience I have had in a few of the MITx ones on edX especially, but also others, has easily been the equal of what I got at the bricks and mortar institution I attended long ago.
That said, some others I have done have been pretty flimsy.