Has anybody started this? what were your experinces with it? did you find it easy?
I just started this recently after learning and working on Dan Chi Sao. I found that even after working my SNT that I still have rather tight upper shoulder muscles. When rolling and my arms begin to tire my elbows tend to float off center. I have to work to keep them there.

What's the difference between this and sticky hands?

It's the beginings of double handed sticky hands. You sort of "roll" arms with your partner learning to keep your elbows centered and keeping yours arms and shoulders relaxed. After we've grown proficient enough with the basics of rolling we begin learning the "attacking" movement of sticky hands that most are familiar with. If you watch 2 people doing the double sticky hands that rolling movement they do prior to making any attacks is what I'm woking on now. It almost looks like they're at a steering wheel.
You'll have to pardon my poor description.