I got an older model just to try it out. It is not truly omnidirectional. It is built as if you had two parallel Rollermouse / BarMouse with a conveyor belt loop in-between the rollers. It is similarly limited in horizontal movement: you can only move it so much to the left and right before it stops.
However, the MouseTrapper is worse at this than the Rollermouse: at the extremes the MouseTrapper moves the mouse pointer quickly to the left/right and the sensing is optical which means that it happens before you get any physical feedback, if you get any at all. Sometimes when I used it it appears as if the mouse pointer starts moving by its own accord, and I found that to be inexcusable.
The "pad" (conveyor belt) is a soft rubber mesh on top of thin plastic guide rails, and depending on where you place your finger, you can get your finger on or between rails. It does feel a bit flimsy and fragile sometimes. Clicking the entire pad is pretty soft and balanced though.
With newer models, you can scroll with the finger on the right border.
Personally, I don't see any real advantage over a capacitative touchpad. Because it is mechanical, it does give the appearance of being somewhat more precise, though... but if I wanted a touchpad, I would rather choose one that had support for multitouch.
