It is just a small ordinary mouse with a dumb bar hanging on the top.
It is even not ergonomic (its advertized selling point), because the scrolling wheel is not on the pen but still on the mouse like a normal mouse. So your finger must fly between the wheel and the buttons, all the time. Further more, the buttons are located too low, you still have to twist your arm, like working with a traditional mouse, to reach these buttons.
Why not just make a real pen without the mouse base? Obviously, there are plenty of space to seat the optical sensor, the wheel and the battery, all within a single pen body. At least, move the wheel onto the pen body and move the buttons higher, then it would be truly an ergonomic and revolutionary mouse/pen.
Modify the back and forward buttons to be scroll down and up. Then I no longer need to touch that stupidly located wheel. A very simple AHK script can do it:
Now I can conveniently use my thumb to scroll up and down, but it is still an awkward device. Swapping left and right buttons might make it more comfortable, but I'm done with it and it is going back to the store.