That certainly looks like a nice machine and will definitely be able to play at a fairly nice FPS.
I am a laptopper as well and I love the freedom, especially since I travel quite a bit (moreso in the summers). You do need to spend a bit more to get a high quality machine, but if you can deal with the form factor it will definitely not disappoint you.
I don't personally have any experience with ASUS, I purchased a high-end
Alienware M15x, but the cost was subsidized by my company. (And i was a thinkpad devotee, before that.)
So if you are absolutely set on a laptop, I would suggest looking around a bit more, but I doubt you will find a much better hardware set up for that price.
Captain Hammer: And these...
[Hammer holds up his fists]
Captain Hammer: ...are not the hammer.
[Hammer walks out of the shot momentarily then walks back in]
Captain Hammer: The hammer is my penis.