I don't think I've ever gotten close to the advertised battery life from any new laptop, Mac or Windows, but I probably use a lot of apps and settings that aren't battery friendly (e.g., I prefer a brighter than average display).
So when I do get 4h of battery life, I'm pretty happy.
Well, I have had _some_ laptops even exceededing their advertised 10+ hrs battery life but only under a _specific_ configuration (basically the one it came with. An OS reinstall would kill the battery life).
Also, things have improved significantly in linux-land. Someone finally had time to turn off unused peripherals in the kernel and battery life doubled over night
So when I do get 4h of battery life, I'm pretty happy.