Circular Runways

I thought this was an interesting idea:

The BBC article is pretty positive but I was wondering what people here thought of it, there must be some drawbacks or it would probably have been used before?

http://boards.straightdope.com/sdmb/showthread.php?p=20070215#post20070215

Existing thread.

Wow, sorry!

Adding more complexity to the most challenging part of flight is counter intuitive.