I've got one MacBook Pro Retina since a couple of months, it came at a modest premium as the replacement to a MacBook Pro 15 non-Retina that couldn't be repaired but was still under warranty; I thought it silly not to take advantage of the offer, and decided to run the risk.
Yes, if you keep the display set to "Best for Retina" setting, Ableton Live looks fuzzy. As does Microsoft Office, OpenOffice, Adobe Photoshop, Avid ProTools and countless other applications, too. I agree.
And yes, it will probably take forever before ALL applications are re-designed to look OK at Retina resolution, literally: some never will, it ain't worth the effort small developers shall put into it, they simply won't see a reason to it and won't do it.
Speaking of Ableton Live, though, of all display settings I rate the "Best for Retina" among the most useless ones: I feel more comfortable with the 1680x1050 that my MBP 15" had (on its hi-res anti-glare display), while the 1920x1200 proved to be the icings on the cake in my experience (for all mix tweaking and playback sessions). On the side, I'm closer to being 50 than I am to 40, and wear prescription progressive lenses.
May I take the occasion to share with you, here, all the beneficial features of the MBP-Retina that were thrown into the box?
Fans, for instance, are really hard to trigger compared to my older MBP-nonRetina: I can push all tracks and plenty of FX here and there, see the CPU load get to 80% and keep it there for ages before I start to hear any hiss; it's the whole aluminum case that gets hotter, and in more places, before fans start to spin in an audible way. Neatly done, that's how I hoped it to be.
Speakers, the built-in ones, are a real surprise compared to the old MBP-nonRetina: I find it now possible to tweak some dialogues, process spoken word files or put together playlists at soft levels, with more spectrum audible than ever, and take a 10 or 15 minutes break from headphones if I'm at private quarters.
External display options are another plus, here: provided one has an HDMI input, I'm able to drive 3 external displays plus the internal, built-in one, in 1920x1200 mirror-mode (presentations and lectures) or discrete/stand-alone (office work or video-artwork-animation). Honestly, I couldn't care less of the fuzziness at Retina resolution with the wealth of options I'm able to access with this, although I understand that the user who just uses the built-in display and wants to take full advantage of the new toy features (and not in expanded-screen-estate-mode) can just be frustrated.
And, skeptical as I was, the performance in terms of stability with the firewire dongle attached to the thunderbolt port is indeed very reliable, and I got away with latencies that seemed impervious to my previous setup; of course, these little things are a real pain to carry around and remember each time you set home somewhere and move again out of it at the end of your session... but they work, and surprisingly well, too.
Sure, the MacBook Pro Retina it's a very expensive piece of hardware per se, but my 2011 MBP with 15" hi-res display was spec'd with the upmost options and did not come cheaper than this at all; would I have bought this Retina without the chance to "cash-in" four-fifths of its value with the non-functioning wreck of my previous machine... that's another question, it deals with the liquidity one has in his/her pocket at a given moment, and this hasn't got anything to do with what the value of the thing itself.
To me, in my workflow, this is the by far the best laptop I even had, and the all-rounder machine with the widest range of applications possible. With a fuzzy image at Retina resolution on Ableton Live, too, that I don't experience in my day-to-day operations.