Product review (4 stars): Fun eventually
I bought these after being disappointed with the small amount of speed I got from my ripstik.  After watching the instructional video on Youtube, and seeing a great deal of fun tricks being done, I wanted to get Freelines.

The first day I bought them, I couldn't help but follow the instructional video's advice of holding onto a sturdy hand-rail and moving myself back and forth with my arms.  Seriously, I couldn't leave that rail until after four or five hours of practice (my time on the rail was split across a few days).

I had two main challenges as a beginner, the first was learning to forcefully twist my feet to steer, and the second was using this twisting to steer both feet independently.  This takes practice.

When I first started moving along a sidewalk, a large problem shows itself: the presence of cracks, twigs, and rocks.  It doesn't take much to stop you if you're putting along at beginner speeds, and that means you're suddenly off of your skates.  Don't worry too much, because if you slip and fall, you just let gravity take your foot straight down and it's on the ground, safe and sturdy.

After a couple weeks, I became comfortable enough to use it as a method of transportation.  My speed feels like a slow run.  Maybe 5 to 8 mph.  Speeds are hard to hold on rough asphalt, but I'm sure I've gotten past 10 mph.

These skates were built for going down hills, where skaters report going well over 30 mph.  All of my riding has been on flat surfaces; I just haven't had time to go out to a hill.

I'm not sure if it's entirely caused by these skates, but I believe I should mention that my knees feel a little worse for wear.

Using these skates takes leg muscle, control, and practice, but for now they seem worth the effort.