My significant other got a 2012 MBA with a 13 inch screen. I really, really like everything about that system. I haven't found the screen to be space challenged at all, which is really a matter of individual preference, I suppose. But I've had a 15 inch screen on my laptops for years now, and I do like the extra screen real estate. I've just had a hard time coming to grips with the pricing for the new rMBP. I think a 13 inch Retina Pro would be a VERY interesting system to consider if the pricing is where it's rumored to be.
Technically, the 15" rMBP has the same resolution as the 13" Air (effective resolution of 1440x900), so while both displays can show the same exact amount of information, the 15" makes it bigger.
And to me that's important, because if a laptop is going to be your only computer then you don't want to strain your eyes if you are going to spend hours on it. I use mine for business, and I easily spend 6+ hours a day on it.
If the computer was a leisure item where I spent maybe 2-3 hours a day a couple times a week then the 13" would've been fine (and that's why I was happy with my 13" Air when I had my iMac for most of my tasks, but less so when it became my ONLY system.)
I know I can return mine, and if for some reason a 13" Retina is confirmed before my 14 day return window has elapsed, but I'm finally getting used to the size, but I'd rather have $400 bucks.
You're a strange person. I guess I just have more concrete feelings on whether or not I am comfortable using something or not. And while money plays a factor in the impact on your wallet, a cheaper price won't make you like using one system more than another.
My advice, since obviously you can afford the 15 since you made the purchase, is pick the size you're comfortable with using on a daily (or whatever interval) basis rather than look at the price.
