IMHO, The best (retina) setting looks awful. Too big..

[marvin4653]

That might be the process. The problem here is that I have not yet witnessed a blurry font in 1680x1050. (But I don't own a MBP). They look identically sharp as in 1280x mode - when comparing same physical size fonts. They really looked very sharp and no indication of antialiasing problems at all. This would be interesting if someone could actually test this properly (I really mean properly, not just subjectively) and present the data.

In my experience 1680-mode is equally sharp as 1280 mode. But this is based on testing in store.

I don't think the font quality in a scaled mode would be described as "blurry." As I said previously, I think the display at a scaled resolution is sharper than a native panel running at the same resolution (e.g., a 15" Retina Pro running at 1680x1050 compared to a 15" non-Retina Pro with a high-res display which has a native resolution of 1680x1050). But I do think the display, including the font quality, is slightly softer at the scaled resolutions than at the Best for Retina setting. Given then that we're talking about display quality that ranges somewhere between sharper than a non-Retina native display and softer than a Retina display running at Best for Retina, this is not text that is "blurry" by any means, but rather blurrier than the absurdly crisp Best for Retina presentation. The continuum would be this:

Retina display at Best for Retina > Retina display at scaled resolution > native
non-Retina display

I provided the theoretical explanation (based on my understanding) that confirms my subjective impression that font quality at a scaled resolution is softer than at the Best for Retina setting. If you wanted to evaluate the results empirically, you could replicate the test for resolution used by DPReview to evaulate digital cameras. Take a picture using a DSLR of reasonable quality, in a manual exposure mode, mounted on a tripod, of the screen displaying a font in the Best for Retina setting, and then the screen displaying a font (increased in size) in a scaled mode. Compare the resulting images using 100% crops of the text.

http://www.dpreview.com/news/2009/10/14/newbox