The hallmark feature of the Couch Mouse lies in its underside. Unlike most mice that use an optical sensor to track your movement, the Couch Mouse has no hole for the sensor to shine through. Instead, the plastic covers the sensor to keep out dust, pet hair, crumbs, and other living-room detritus that can become lodged inside the mouse and disrupt the sensor's accuracy.
The benefits to such a design are clear, but Logitech has also addressed the negatives, designing the plastic covering over the sensor in such a way that scrolling is as smooth as with a standard mouse. Logitech does recommend using a mouse pad if you intend to use the Couch Mouse on a glossy surface, but we had no problems using it on a wooden desk with a shiny polyurethane finish.
Also unique to the Couch Mouse is its hand detection technology. If the idea is that you will use this mouse on a soft surface that you and others might be sitting on, it's reasonable to assume that the mouse might end up on a blanket, a pillow, or otherwise mixed up in your seating arrangements. With the hand detection technology, the mouse won't activate unless someone is gripping it, which ensures that it won't accidentally click and disrupt whatever you might be watching or listening to. That feature also conserves battery life. Logitech claims that the pair of standard AA batteries included with the Couch Mouse will last for around two years. Remind us in 2013 and we'll try to report back.
We also like that Logitech has added its HyperScroll wheel to the Couch Mouse. Normally a feature reserved for Logitech's higher-end mice, the HyperScroll wheel offers the best scrolling experience on the market. In its standard mode, the wheel has the same ratcheted scrolling action of any typical mouse. Press in the scroll wheel, and the wheel spins freely, letting you zip down long Web pages almost instantly. Throw in the side-to-side tilting feature that lets the wheel act like forward and backward buttons, and the Couch Mouse gives you an impressive array of options for navigating Web pages, lists, and documents quickly.
Logitech's Couch Mouse M515 isn't the most innovative living-room product out there. It doesn't have a gyroscope or a built-in keyboard, and you can't use it as a universal remote control. What it lacks in high-end features, it makes up for in functionality and sensible design. You can certainly get away with using a standard wireless mouse in your living room, but the Couch Mouse M515 will offer a significantly improved, sensor-obstruction-free experience for a reasonable cost.