Apple’s refurbs come with a new outer shell and new battery, meaning you get same-as-new appearance and performance. Better still, you get the same one-year warranty Apple extends to new hardware. There is literally no downside.
But there is one small cosmetic difference: refurbs come in nondescript cardboard boxes, not the fancy white ones afforded to new gear. Big whoop, if you ask me.
Apple’s refurb offerings and inventory change over time, so you can’t always get what you want. But I think it’s the only logical place to start your shopping. I’ve purchased refurbished iPhones, iPods, and iPads, and every one of them arrived in perfect, like-new condition. Consequently, when it comes to Apple gear, I can’t see any reason to pay extra for the new stuff.