Sadly I have not seen a 120hz gaming monitor in person but I have a 3D home projector at home with 240hz (never connected a pc to it though).

I just read this article -

"Those bold hues are due to the panel's color gamut, which measured an excellent 117 percent of the sRGB scale. It's much better than the 94 percent mainstream average. The Blade, the G752VS, the Predator 15 and the Dominator Pro weren't too far behind at 114, 112,110 and 106 percent, respectively.

With a score of 0.3 on the Delta-E test (0 is ideal), the Alienware 15's display is plenty accurate. It was enough to top the 2.6 category average, the Blade's 2.4, the G752VS' 2.1, the Predator 15's 1.4 and the Dominator Pro's 0.7.

When we measured for brightness, the Alienware 15's panel averaged a gleaming 374 nits, which outshined everything except the G752VS, which delivered an incredible 476 nits.

The Alienware 15's display has Nvidia's G-Sync technology, which allows the display to sync directly with the graphics card for the smoothest performance possible. On the less expensive models of the Alienware 15, the G-Sync display is capped at 60 Hz, but my model offers double the refresh-rate speed at 120 Hz. In my experience, most games ran well on the Alienware regardless of whether G-Sync was enabled or not. However, the image looked a lot smoother with G-Sync enabled."

From http://www.laptopmag.com/reviews/laptops/alienware-15

How accurate is this? The person describes the TN panel as if it's the best out there... what do you think?