Although it may be ergonomically correct, this mouse's upright form takes some getting used to. The left side of the mouse has a concave area where your thumb falls, but on the other side of the mouse, the rest of your hand must fight gravity to stay upright. This lack of support leaves the side of your hand dragging as you move the mouse--something we grew tired of quickly. The VerticalMouse 2 has three main buttons and a scrollwheel on the right side. A button on the left side--just above the thumb rest--is intelligently placed. The scrollwheel, which also functions as a button, is smooth--which we like--but gamers and others may prefer the tactile response of a clicking scrollwheel.
Unfortunately, we encountered a problem with this mouse that we've never seen before: the rubber around the scrollwheel separated from the wheel and nearly jammed up our test unit. This design flaw could prove to be a major problem, as we had to pry up one of the mouse buttons to recover the loose rubber and replace it on the wheel. The buttons themselves require only a very light touch, which makes them slightly more prone to accidental hitting. Four of the five buttons are programmable when used in conjunction with Microsoft Windows operating systems and the VerticalMouse Manager Software, but the left-click button (actually the top button, in this case) isn't programmable.
At 3 inches tall, the VerticalMouse 2 tends to get in the way when moving your hand from the mouse to the keyboard and back again. We chalked this up to our familiarity with flatter mice, but we did send the VerticalMouse flying across the desk on more than one occasion, even after weeks of constant use.
Looking past the design, the mouse's 1,000-dots-per-inch optical sensor is very accurate and sensitive. It works on almost any surface that isn't shiny or metallic and never jumped or skipped in our tests. We did, however, find one major issue with the mouse's operation: when our test computer woke up from sleep mode, it didn't recognize the mouse--a problem we've never encountered with a wired mouse. We had to unplug and reconnect the mouse every time in our tests with two different Windows XP systems.
For everyday or occasional use, this mouse could provide relief for those suffering from repetitive stress injuries, but we can't recommend it as an ideal alternative to a good-quality traditional mouse.