The one problem I have with this thing is (besides the need to buy a $80 adapter just to use your USB) the price.
This Macbook is certainly not worth the $1299 for what it does. I can get the current gen Macbook Pro for the same price and I dont need to buy an adapter for my USB and it can do 3x as much. Just saying.
Except if you have to carry around the laptop all day, the new MacBook positively destroys the rMBP. Don't get me wrong - I have a 13" rMBP and love it, and the new MacBook isn't enough for me. But there was a time when it would have been. I, for one, bought the original MacBook Air when it first came out, and don't regret it for even a second. It was ahead of its time, and just amazing. One of my favorite Apple purchases to date.
For one thing, I can see a bunch of university students loving the new MacBook. Carrying heavy laptops around gets quite tiresome..
So it's not for everyone, and - like the original MacBook Air, it's definitely a glimpse into an Apple-notebook future. It'll be glorious.