The thinness is the critical problem, and to be honest with most consumer electronics (phones especially; please give me a larger, replaceable battery), I wish they would stop the race to the bottom and instead deliver more functional and longer-lasting productions.
I have an rMBP 15" and a 15" Lenovo Y500. The Y500 cost less than half of the rMBP for equivalent performance but the experience, battery, screen, trackpad, etc are of course much better on the Mac. But for intensive tasks, even with nearly identical internals and the same OS, the Y500 is far more pleasant to use. Say what you want about Lenovo and the terrible things they've done to their laptops in the last few years, but the Y500 is designed to expel heat in the least obtrusive manner possible and it does an amazing job.
At full bore, all cores, maybe a game, the Y500 happily pushes a lot of air out the side vent, and the keyboard, trackpad, bezels, etc., stay very cool.
With the same workload, the rMBP gets very, very hot and seems to blow a small amount of air out of the keyboard (?), occasionally burning my fingers, It's loud and very uncomfortable to use.
In a sense it definitely makes me feel like I overpaid for the extra speed, since I can't use it comfortably anyway.