Good deal?

That model costs $1,159 refurbished from Apple, so for a new-in-box one that's pretty good.

11" or 13" ?

It's an okay deal, considering it's brand new. It can be found a couple hundred cheaper used, but if you want the full warranty (and chance to add AppleCare), that's what makes this worth getting.

Also, just because Apple prices refurbs a certain way, that's not necessarily the best litmus test especially for older models as their pricing doesn't reflect actual market trends and can sometimes be off by several hundred dollars on older models.