As I already mentioned in a recent post I bought a new rMBP. I'm not going to write a full review (when do I ever?), there are numerous detailed breakdowns by many individuals far better qualified and experienced than I; but I will offer a few opinions.
(Most of the) Hardware
The hardware in this thing is pretty high-end, and the machine (even the lower-end model) benchmarks exceptionally well. It performs beautifully on everything I've thrown at it, though I am not the most challenging of users. The biggest thing I have thrown at it is EVE Online running at maximum resolution. It performed without a hint of stutter or slowdown (though it did run hot). I probably wouldn't play for a long period on these kinds of graphics settings, but the machine can handle some serious visuals. It's hard not to be amazed by how good the game looked at this resolution (all graphics optionals maxed out bar antialiasing).
It's not just the performance however. This thing is thinner than my late 2008 MacBook Air (at it's thickest point), if only by a millimetre or so. It is spectacularly slim. So slim in fact that all of the MacBook Pro sleeves I've looked at so far are designed for the non-retina model, and are a little too loose for my piece of mind. Finding a travelling solution I am happy with is going to take a little time while manufacturers catch up.
Oddly, I am aware of the lack of "MacBook Pro" text at the foot of the screen, which is instead etched into the underside of the unit. It adds to the minimalist aesthetic, but is noticeably absent - likely due to simply being so used to having that text in my peripheral vision for so long now. I can't overstate my love of the design - this is the most beautiful computer I have ever owned.
Apple quote 7 hours of battery life. I've found that if I'm just browsing the internet or word processing then this is probably a fair figure. Certainly after about five hours of continuous use I only managed to hit about 30% battery. That's pretty awesome. I would expect to get a days use, for sure. There are a few reports floating around the blogosphere of battery-draining bugs introduced in Mountain Lion and as always your mileage may vary.
This is the big deal, the main attraction, and yet oddly as a feature it rapidly fades from your mind. The screen is so beautifully clear that it does at times feel like you're reading from illuminated paper, and the contrast and black is so good that the display blends into the slim bezel almost perfectly. If you really look, you can spot the transition, but if you're not expressly focused on it, you'll never notice it. I have a 24" Packard Bell display on my old Windows rig that impressed me with it's contrast and refresh, but it has nothing on this. There's not even the slightest hint of ghosting to be seen.
The most immediately apparent improvement in graphical quality comes from the dock icons; though it'll be text rendering that really makes the difference. It's hard to explain just how smooth and crisp everything looks. After a while, as the initial novelty fades, it just becomes a great viewing/reading experience and you kind of forget about it.
You'll notice the instant you look at a lower-definition screen.
I couldn't go back to lower-DPI screens (after using a retina iPhone and iPad screen also). The "cost efficient" monitor on my work PC makes my eyes bleed now; it's like playing Skyrim and marvelling at the incredible landscapes and then being told you have to play eight hours of original Pac Man per day. It really is a first world torture. Luckily, I'm pretty certain that Apple have set a bar that will be the standard in twelve to twenty-four months time and with the increased mass production screens like this will becomes more and more affordable. Retina quality displays will not be a distinguishing feature for very long, and pretty soon this machine will be incorporated into the basic MacBook Pro range.