The Space Navigator as most are probably aware is a peripheral device that is supposed to help with navigation in a 3D environment. The basic model, at $60 is certainly affordable and was the reason it was tested out, but unlike software applications, there isn't a free 30 trial, so this was tried and if it were good, the higher up models would have been evaluated afterwards.
It turns out, if this was an introduction to the product, it was off putting enough that after every artist tried it, it just got dumped on a shelf, never to be used again and put paid to any notion of bothering with any other products.
The theory is good, being able to seamlessly navigate your scene, rotate, zoom and pan all at the same time and have simple shortcuts at your finger tips.
The reality, it was too clunky to control, the drivers were rubbish and interfered with any custom layouts and short cuts. It was tried out with 3DSM 8 and 9, ZBrush 3 and a few other programs. It could well have improved since then, but the actual hardware interfacing with the device just wasn't very comfortable either.
I will say, it worked really well with Google Earth though, and it could be worth a poke if it has been significantly improved since it was evaluated. It's a shame that this device didn't live up to expectations nor filled us with confidence to spend the considerably more money on the higher range line of products.