I have no intention of riding this, ever, but I like reading the ride reports. It always sounds far worse than PBP.
It's the weather that can make BCM tough and the sleep deprivation that can make PBP tough (in my limited experience) although I found the relentless rolling sections of PBP more energy sapping than anything on BCM.
Apart from the circus/support aspects of PBP nothing about it comes close to the first 300km of BCM, that first day, 2010 in particular, ranks as my best day's cycling ever. Climbing Pen-Y-Pass in the setting sun will take some beating. Certainly those long French roads don't ever come close.
To anyone doing it for the first time - As you are approaching Pen-Y-Pass in the dark then yes, those
are bicycle rear-lights in the sky, it's not an aircraft, and yes, someone about an hour behind you will be wondering the same thing about your rear lights.