I tried to use a coworker's Lenovo the other day and the offset keyboard drove me batty. I couldn't imagine trying to use that one on a lap-pad.
[1] http://www.toptenreviews.com/computers/gaming/best-gaming-la...
If you compare the iPhone with what existed at the time, doing your own custom very integrated and very compact logic board, allowed a massive screen and a massive battery. That was a game changer.
They are just trying the same trick, only I'm not sure (to be polite) that it brings any real competitive advantage. Sure a thin, ultralight and still powerful laptop would be appealing. But the MBP is just not that smaller or light compared to the competition or even the previous generation. Especially not the 15in version.
It is just a lot of sacrifice for a perceived marginal improvement over the competition. Nobody would be complaining if the 15in MBP weighted 1.5 pound and still lasted 10 hour with a quadcore i7.
Don't forget a good, centered, trackpad (apple is fine on this front, but many competitors are not) and keyboard with the common keys but no numpad.
Couple these two things with a clean-looking, sturdy build in a 13,3 inch laptop and my money is yours to take. I can atand the weight/thickness of pre-retina macbooks no problem.