I just bought myself a MacBook! I got a refurbished one (some 20% off retail), and I must say that I’m absolutely delighted at my purchase.
Getting refurbished does have its risks, as explained on this page on the Apple’s website. The risks associated with refurbished products are generally aesthetic, with things like scratches or discolouration.
Happy to say, mine has been free from both.
So, if you’re thinking of getting a refurbished Mac anytime soon, I say go for it. If you were thinking of getting a Mac, and don’t mind getting a refurbished one, I say go for the refurbished one and use the savings you get over retail to upgrade your parts.