Macbooks have much better build quality than most laptops on the market. No cheap plastic, the keyboard works well (if you like the layout), the trackpad is peerless, and the screen is somewhat high quality. Some professional grade Windows laptops offer similar quality, and the odd consumer laptop like the Sony Vaio S, but most Windows laptops marketed towards consumers tend to be built horribly. You're paying a lot for build quality and aesthetics if you want to use a Macbook as a Windows laptop, but to some people it's worth it.
All that said, I only use Windows to run programs unavailable on OS X, and so far I've avoided installing a Windows partition on my Macbook.
All that said, I only use Windows to run programs unavailable on OS X, and so far I've avoided installing a Windows partition on my Macbook.