With an iFeel mouse, every icon, scroll bar and other windows component causes the mouse to “rumble” slightly when you move the pointer over it. The movement can be made so weak as to be barely noticeable or quite strong. You can even customise the feel of each vibration, with "Immersion TouchSense" themes such as "Metallic" "Rubbery" or even "Spongy", although I stuck with the default setting which was a little less distracting. If you're sick of the mouse vibrating slightly when you move the pointer over an icon but want it to keep doing so with regular windows buttons etcetera, you can stop it doing so by using the iFeel customisation program. You can even turn off the Immersion technology to stop the mouse from vibrating on its own accord ever again, although that'd mostly defeat the point of buying the thing in the first place.

Question is, is it worth buying over a regular mouse? And my oh-so-vague answer to that is… maybe. Personally, after dropping the strength of the vibrations it actually became relatively useful. Of course you can still see the pointer as it moves over an icon, but once you get used to it, which doesn't take that long, the mouse briefly shaking each time you do move it over an icon or other Windows widget actually acts as a subtle and useful tactile “hint” that you're over an icon, along with the what you see on screen. It's not going to change the way you use a mouse, but it can be useful, especially if you're new to using a mouse.