One area where Microsoft hasn't held back is with the mouse's Teflon feet, which are much larger than the X8's. Their large surface, broad coverage and thickness gives a lovely smooth feel on most flat surfaces, matching even the most expensive gaming rodents available. In general there are no complaints about the X3's build quality either, though it doesn't feel as solid as Microsoft's other mice. Last but not least, the mouse's two-metre USB cable is certainly long enough for most scenarios.
Overall then, the X3 is a basic but decent gaming peripheral. However, this £26 mouse lacks so many of the features of its pricier brethren that for most the saving probably won't be worth it.
Logitech's G9, for example, is currently available for around £40. That extra £13 gets you a better-built mouse with interchangeable grips, more buttons, a higher resolution sensor (3,200 DPI compared to 2,000), Logitech's excellent Micro Gear four-way scroll wheel, internal memory for portable profiles, a braided USB cable and funky adjustable backlighting.
Since we reviewed it Microsoft's own X8 has also come down in price a little and can now be found for around £55. Admittedly this is nearly double the price of the X3, but keep in mind you get 12 buttons, a metal four-way scroll wheel, weight cartridges, an LCD display for sensitivity, a 4,000 DPI BlueTrack sensor which should work on almost any surface and best of all, the option to either play with a wire attached or to go cordless with three-days' worth of battery life.
Of course the one exception here is southpaws, for whom the above mice aren't options. If you do belong to this rather limited demographic you're not exactly spoilt for choice and in this case the X3 is definitely worth considering, though you might also want to check out some of the competition from Razer.
It's not a bad mouse by any means, but unless you're a southpaw there are alternatives to the X3 that don't cost considerably more but offer a greater breadth of features.