I looked through their Web site. I'd like to try one to see the difference from an ellitptical trainer. I'm really only familiar with the Precor elliptical which provides a sort hybrid motion between pedaling and running. The ArcTrainer appears to be a hybrid of running and stairstepping? I don't know. I'm not sure I'd like the back and forth. I like to have a bit of up and down too.
The Precor device will let you change incline too.
Another trainer that Precor has which my gym uses it the Adaptive Motion Trainer. It's sort of an elliptical, but you can change the motion on the fly, making more of a stairstepping range of motion or something more akin to what I see in ArcTrainer, and every range of motion in between.
I confess I've gotten away from ellipticals and such, preferring to use equipment that mimics the sports activities of running, cycling and rowing. I use the elliptical lately only for warmups, however it IS the only exercise I like to do while wearing headphones, so if I feel I need some music motivation, I'll choose the elliptical-type trainer over something else.
Still, I'd love to give the ArcTrainer a try. Neither of the gyms I use have one though. Oh well.