What makes the X8 such a joy to use is the technology powering it. Like the Explorer mouse, the X8 uses BlueTrack technology, which is - as experience shows - a notable improvement on optical and laser.
But why the improvement? Well for a start, BlueTrack's blue LED light has a shorter wavelength than red light which can thus resolve detail to a greater degree. The blue light is also diffused and broader which helps not only to illuminate more of the surface, more evenly but also in effect increases the contrast between features and textures within that surface. This combined with a sensor and lens that can distinguish the finer differences in reflected light make BlueTrack mice more accurate as well as functional on a variety of surfaces, including smooth shiny ones.
However, what's really important is how the X8's 4,000dpi sensitivity translates into actual use. My first thought, on reading the original press release for the X8, was definitely "who on earth needs 4,000dpi" but having used the mouse I'm a sceptic no longer - the precision afforded is simply fantastic. Even if - and Microsoft agrees here - the max acceleration of 75g and 120in/s movement speed with which the X8 can cope are more than anyone could ever produce.
Gaming is an absolute pleasure with the X8. Its high-sensitivity gives great responsiveness in first-person shooters and that isn't lost when more precision is needed, say after pulling out a sniper rifle. Being able to script a macro to switch weapon and sensitivity at the same time is just icing on the cake.
Mice are tricky, highly subjective products to try and rate, but I'd definitely pick the X8 over the Steel Series Ikari which is going for around the same money, or my previous mouse of choice: Razer's Copperhead.
Microsoft's SideWinder X8 combines the best aspects of both wired and wireless mice, adds its funky, high-sensitivity BlueTrack technology and wraps it up in a slick, ergonomic package. Put simply, the X8 is the gaming mouse we've been waiting for Microsoft to make.