Yes, it works absolutely fine. Slow down the Mac? No, when you're running Bootcamp you're only running Windows, and it runs very quickly indeed. You will get rubbish battery life because it doesn't support the integrated graphics (yet). It's possible this might change in the future. It can't "affect the hardware", you're just running programs on your computer... unless you count increasing the temperature and the theoretical possibility that the longevity of the computer might be affected by this (not something I would think you could easily prove).
But I agree with poster 2, if you don't need ultimate gaming speed then run Windows virtually, using Parallels or VMWare or VirtualBox (which is free). This works fine, and you have them both simultaneously.