The best?
Let me count the ways it's so very good:- Four programmable keys- A hand-fit that's remarkably ergonomic, but also stylish- That great Kensington software that allows near-limitless customization- Easy navigation- Easy-to-use scroll ringIn fact (at least for my hands) this may be close to the perfect trackball. I noticed a considerable divergence of opinion in the reviews, but I suspect that the reactions would be unanimously positive if this were optical. As it is, fibers and dirt can clog the trackball; if left uncleaned too long, the damage might ruin your mouse. And while fairly smooth in operation, it's not close to Kensington's optical versions.