Compared to the Microsoft mouse, the Evoluent design cants your hand up at a more severe angle, positioning your hand nearly perpendicular to your mousing surface. The idea is that gripping a traditional mouse makes you twist your forearm in an unnatural manner. Ideally, ergonomic experts say, you would grab the mouse so that your palm is about 90 degrees to the table top. If indeed it's true that the closer to perpendicular the better, the VerticalMouse 3 does a better job than Microsoft's mouse at keeping your hand and forearm in the proper position.
About the only advantage the Microsoft mouse has over the Evoluent model is that it's wireless. The thin USB 2.0 cord on the VerticalMouse 3 isn't too annoying, but if you've made the transition to a wireless mouse already, it might be hard to go back. The Microsoft mouse also has some more-refined features like two thumb-side buttons and a tilting scroll wheel, but the VerticalMouse 3 compensates for those deficiencies by making its thumb button very easy to reach (unlike those on the Microsoft mouse), as well as giving you three main mouse buttons and a scroll wheel. We don't really miss the scroll wheel tilting, but the Evoluent mouse would benefit from a second thumb-side button.
Still, Evoluent gave this new mouse some standout features that are missing from its previous incarnations and the current competition. For one, a new optical sensor gives your four preset sensitivity settings, which you can scroll through via a button on the bottom of the mouse. We normally prefer DPI toggle buttons sit on the top for easy-access, but if it has to be on the bottom, we like Evoluent's solution: it uses colored LEDs to indicate the current sensitivity, with options ranging from 800 to 2600 dpi. Its new scroll wheel also has distinct "detents" which gives your scrolling tactile feedback as you move between increments (gamers especially will appreciate this feature, as it lets them scroll through different weapons more easily).
In addition to improvements to the casing, Evoluent also claims to have improved the feel of the buttons, as well as the internal electricals. With the VerticalMouse 2 having been reviewed by another CNET editor who's no longer with the company, we can't comment on the updated feel. We do maintain the criticism from the last model that left-handed users get short-shrift. Our complaint last time was that the left-handed version of the VerticalMouse 2 used to cost $30 more than the right-handed model. Now, there is no left-handed version of the VerticalMouse 3. Instead, you can pay $80 for a left-handed version of the older VerticalMouse 2.
Finally, Evoluent says it has added more functionality to the software, giving you the option to program button-command profiles specific to different applications. Microsoft's software doesn't give you that option. We don't imagine that many people will take advantage of the application-specific programs, but for those who do, this flexibility should be more than welcome.