I ordered mine at about 6PM EDT on launch day and received it yesterday. The Apple Store in Ottawa has had stock intermittently since last weekend, but they don't have the config I wanted (base with 16GB RAM).
I'm still setting up the machine the way I like it, but it's really case, and the display is awesome. I love 1920x1200 mode, and aperture looks great. I just need to get Photoshop on it to see how it behaves on the retina display.
I calibrated the display, and the colour gamut is pretty much 100% of sRGB. That's pretty good for a laptop, and the best Apple had used to date, but still inferior to the Dell Precision m4600 PremierColor I also have (which even exceeds AdobeRGB gamut). Sharpness is unrivalled on the Retina, so it pretty much comes down to detail vs. colour gamut between the two.
USB3 is fast, but not quite as fasts I thought it would be. A SATA3 SSD in an enclosure maxed out at about 150MB/s. Perhaps it's the controller in the enclosure also; I know that drive can do 400+ MB/s on an internal interface. I'm still not certain whether I will be OK housing my 700+GB photo library on a USB3 drive. If not, I will be on the lookout for a portable thunderbolt drive.
Form-factor wise, this is not an Air like some people seem to imply it is. It's thinner than the old MacBook, but it's still substantial. I may end up keeping my original 11" Air to use in certain circumstances like in a car or plane.
