I have owned every full-size iPad. With iPad and iPad 2, I obsessively protected them with all manner of cases. Full-body Invisibleshield, Otterbox Defender, Apple Smart Case, Speck Folio...you name it. Then with iPad 3, I decided to just "wing it" and use it case-less.
Did that with iPad 3, iPad Mini, and now my Space Grey iPad Air. No scratches, because these things are durable. It goes everywhere with me and gets set down on counters and thrown into my messenger bag (I'm a college student). Two months in with zero scratches and I don't expect any.
So just let it go and use it. If you are careful with your electronics and you have some form of insurance, too (renters, AppleCare, or otherwise), just use it without a case.
So, short answer is
"no, it does not scratch easily."
I'll include a picture of the back of my iPad for proof (used since launch day).