It's a mechanical keyboard, so has a fair few advantages over standard cheap membrane keyboards.
There's a clear tactical and audible sound at the point where the keypress is registered, meaning that you just naturally type more quickly and accurately. It feels far more precise, and I guess 'clean' than using a membrane dome keyboard, which is typically pretty mushy in comparison. For obvious reasons it's sort of hard to convey in text, and it's more something that you'd have to experience yourself by typing on one (the best analogy I could really give would be it's like the difference between playing on a cheap-ass no-name electric guitar and an authentic Fender). They also are far more reliable and have a far longer life expectancy than membrane keyboards. Plus it has N-key rollover, meaning that inputs don't get dropped if I press too many keys at once or in the wrong combination (normal keyboards have issues with this because of the way they are wired).
Plus the mechanical switches have less debounce time. Typically with membrane keyboards you need a delay after the keypress to allow the button to settle and confirm that it was a definite keypress and not accidental - this adds a delay into the input. It's not particularly noticeable during typing but when playing Tetris and a few other games where timing can be important it's noticeable. Except I don't really reap the benefits of this so much because my laptop only has USB ports, and using a keyboard through USB instead of PS/2 adds lag that pretty much negates this anyway, so using my laptop's in-build keyboard (which is equivalent to PS/2) still has less lag for Tetris.
It was pretty expensive, but I got a fair bit of money for Christmas, and I figure that given I'm going to be using this every day for ten years it's actually not particularly bad value for money.
