So how will my code editor look on Retina? All blurry?
That is the issue I am having. Eclipse-based IDEs are not ready for Retina. The text is legible, the IDE is usable, but its noticeably blurry. I've logged a ticket with Aptana Studio and Eclipse, but they have no solution to this issue, just workarounds which don't really work. If you are using Vim or a simple text editor, however, there is no issue with the appearance of the text. Xcode works just fine, too.
I am running that way right now, using Firefox zoomed in slightly, and it works beautifully. SwitchResX lets you set up hot keys to switch resolutions too, so I've been switching back and forth between 1920x1200 and native resolution trying to decide what I like best. So far, I think 2880x1800 is winning, with Firefox zoomed in, and a 14 point font (Inconsolata) in Emacs and iTerm2. Though both of the latter work correctly at Apple's scaled resolutions already (I've so far settled on Inconsolata 11 at 1920x1200)
For me, the biggest thing that's changed is that I've used Monaco 9, or variants thereof on non-Apple platforms, as my code font for the last 15 years. This was already too small for some people to read, and I've had hotkeys set up to switch to larger fonts when showing other people code on my screen for years. Monaco 9 doesn't even really exist at scaled resolutions though - it is NOT the same font you get if you render any other point size of Monaco, which is what happens at Apple's scaled resolutions. "Monaco 9" looks like the rest of Monaco now. (Techincally the old pixel version does still exist when running at native resolution, but it's crazy small and although I can read it with some effort, it's not really practical). But the screen is so great that I'm finally over my obsession with pixel fonts. Inconsolata is a fantastic tiny font when the pixels are too small to see. I'll probably try a few more now that I've been liberated, that was just the best I happened to have installed already.