Long post time. I got in a stock of Retina MacBooks; here are some impressions:
1) The screen is amazing. Like, unbelievably amazing. Easily the best laptop screen I have ever seen, and I've been in this business for over 20 years. That said...
2) Apps that do not take advantage of the Retina look bad; worse than a regular Mac. For a simple example, I brought up the same web page in Safari and Firefox on the Retina, and on my regular 15" Mac. On the regular Mac, the page looked fine. In Safari on the Retina, the page looked stunning. But in Firefox on the Retina, it just looked bad. Lots of stair-casing and anti-aliasing artifacts. As apps get updated this should get better, but for now, about one month in, it's not so good.
3) I was surprised how fast the Retina Mac is. My older Mac is no slouch, with 8 GB RAM and an SSD, but the Retina with its Core i7 processor and other improvements is noticeably faster, and makes my regular Mac (which I previously thought quite speedy) feel sluggish.
4) Multiple monitors on the Retina is super cool and super easy. I plugged in three externals (two via Thunderbolt, one with HDMI using Monoprice MDP-to-DVI and HDMI-to-DVI cables), and they all popped up perfectly at optimum resolution. I could rearrange them however I liked in the Displays system preferences easily. However...
5) Multiple monitors really points out what I feel is a profound weakness of Mac OSX vs Windows -- the menu bar sticks to the top of the primary display. This design fails miserably when your active window is three screens over, and you need to access something from the menu. In the Windows world, where the menu sticks to the top of each window, this is a non-issue. If Apple is truly going to finally embrace the multi-monitor world, they should make this an option in a forthcoming OSX version.
6) Much has been written about the lack of an optical drive and ethernet port. Honestly, this is probably no big deal for most people. My regular Mac has a broken optical drive, and I think perhaps five times in the past year I missed it and had to seek out an alternative. When I've got a 32 GB thumb drive on my key chain (=about four DVDs, or one BD, or pretty much the full series of Game of Thrones in HD), it's just rare that I need a disc for anything. My company has already deployed a whole bunch of Airs, and I keep a few Superdrives in inventory just in case someone needs to read a disc -- it rarely comes up.
Ethernet is a bigger deal, in my opinion, but the Thunderbolt-to-GBe dongle solves this OK. I already keep a variety of dongles in my backpack (MDP-to-VGA, MDP-to-HDMI, etc.); one more won't kill me. Or, just leave it attached to the cable at one's desk -- you have to plug in when you sit down anyway; it doesn't make a difference if you plug in with an Ethernet jack or with the dongle. Only downside is if you're rocking the four screen configuration, you can't do this.
7) MagSafe 2 pisses me off. There was nothing wrong with the old MagSafe, and the old MagSafe would have fit just fine on the Retina (it fit on the pre-2012 Airs, and no one complained). I think Apple changed it just so they could sell more $79 power supplies. I've got lots of extra MagSafe 1 supplies; now I gotta spend a bunch more money to get spare MagSafe 2 supplies. And don't tell me about $10 adapters -- that little bugger is guaranteed to get lost on a typical business trip. The only place I'm using them is on Thunderbolt displays (with their infernal non-replaceable cables), and even there I'm thinking about Krazy-gluing them into place.
8) Cost-wise, the Retinas are not as expensive as they first appear. If you take a regular 15" MacBook Pro, upgrade the RAM to 8GB (std on the Retina), upgrade to SSD (std on the Retina), and pick the higher resolution screen (which is still not even close to Retina), then the price becomes comparable to the Retina. Since I usually buy 15" MacBook Pros anyway, I will probably only buy Retinas from here out. Hopefully my Apple rep will give me my discount back -- I placed this order on the first day, and got the discount, but then she called back later that day and told me that she'd honor the discount for this order, but because of the overwhelming popularity of the Retinas any future orders will be at full retail. I suppose that will subside in time.
Cheers!