A rubbish system that requires you to purchase an expensive (£50) adaptor in order to power your laptop, giving you another item to lug in your carry on, and more cabling around your seat area in-flight. And it's unreliable.
I've always found the empower to be fairly reliable. I have the Kensington kit for my apple powerbook and it's only really a tiny pouch that takes up next to no room at all.
Chris