You can fit a lot more stuff on the screen: terminal windows, word documents, web browsers, etc. In that respect it is much like the IBM T221 (9 Megapixel) monitor. However, since the screen size is 21", everything is (you guessed it) smaller. So for regular work I would prefer the Dell 2405 or Sony SDM-P234.
However, it is an LED LCD, so there are cases where the improved color gamut is worth it. In those cases, there are people who are willing to spend the money to buy it. In my case, I like to investigate bleeding-edge technology to see where it can be used to solve problems. See my Quake3 resolution? We have used that to solve problems that are too big to be otherwise solved. Quake 3 was just a "fun" thing we tried to prove it worked.
It is more expensive, so it will never take over the regular LCDs until the price comes down.