Product review (4 stars): Finally starting to get it!
Not sure I have much to add considering what has already been touched on, but I will share my own experience with these unique skates. First, there is definitely a learning curve and plenty of practice seems necessary to get the most out of these. I still consider myself a bit of a beginner with these even after testing them out a dozen or more times. What I have finally learned through my own trial and error rather than seeking any real tutorials or lessons is that you really must learn to propel yourself with your full body, with special focus on your core. If you twist your torso you can really whip the rest of your body (legs) into getting acceleration.

For the longest time, I tried to create momentum with mostly my legs doing the twisting and S motions but this wore me out and made my legs sore. Using your torso makes it so much more effortless. So, I think it is the combination of the two techniques that really makes the skates go fast and accelerate quickly.

But having said this, you still have to learn to balance and do the proper leg motions if you are just starting out. The rest will come along the more time you spend with them I believe. Also, be sure to use quality skate bearings (bones reds anyone?)

*Update/Addition*>>>

1/2016:

I just wanted to mention that I just purchased a pair of Xgliders caster skates and find them to be a breeze to use and seemingly much easier than freelines, at least for cruising around on in general. The Xgliders don't seem to require the leg rotations specific to freelines which makes sense as the wheels already rotate. It seems that simply shuffling your feet alternating the left and right forward and backward (in and out) gets you going with minimal effort. The faster you do the shuffling motion the faster you go and all of a sudden your going crazy fast while just on flats. Turning is also very easy and traveling at slow speeds is still very stable. So, if you think freelines may be too much of a challenge and just want to get moving around well enough, I would suggest the Xgliders. They can accommodate up to 90mm inline wheels which is also a plus.

Cheers