To test the battery life we put the machine through two real world situations. Firstly we tested the machine while browsing the internet with WLAN enabled (General). Secondly we tested the machine while gaming with SLI and full brightness active.
The battery life under general duties is quite impressive for a gaming laptop, although this is significantly reduced when you do try and game on in it.
ASUS do some great gaminmg machines too, and they cost a lot less than Alienware, but at least Alienware put a lot of effort into the looks as well, which is important.
Great machine, I own one, been using it now for gaming for a month. runs a bit hot on my knee, so I use it more on a desk.
The problem with Alienware laptops, of which I have had many, is the hinges wear out so soon. If anything needs replacing it is absurd at costs.