This guy says otherwise about the build quality. Further, only the 15 inch rMBP has quad core. We are comparing the 12 inch MacBook.
it often sems to me that windows computers are a better deal on the front end, but over time, when you factor in time and money for repairs (every computer i have owned has needed them), the gap isn't so large (a problem with my rmbp took a few hours to fix last year, and one with my rmb took a few minutes -- both were at no cost). and, i've generally found my apple stuff is more dependable and lasts longer. your mileage may vary. maybe the razer is perfect. i don't know.
the rmb is made for different stuff -- if you want a super portable gaming platform, the razer looks like your machine. personally, i prefer apple because of the ecosystem, ease of use, and support -- it's effortless to do work. i don't game, so the rmb's "deficiencies" are irrelevant to my use case. i've been on international trips with it several times, and it more than made up for its price in lightweight / long-life / solid performance.
perhaps, if i could find the stuff i need for my work in windows (haven't yet, but i'm keeping an eye out), the only computer that would tempt me is the surface pro. that's a whole other conversation, though. at any rate, gamers *can* use the rmb, but you'll probably get more bang for your buck elsewhere.