Yesterday I got to try a new MacBook Pro and a MacBook Pro Retina side by side at an Apple retailer. (Not a full Apple store as they don't exist out here in the sticks.)
Both machines were outfitted with the same processors, speed and RAM. The MacBook Pro had the lowest screen resolution option. I could not see any difference between the two with them set at the same resolution. With the Retina set at more work space, e.g., higher resolution, I did not like it as things were too small. Quite frankly, I can't see pixels on the 1440x900 screens so any more than that is a waste to me. To see a pixel I need a magnifying glass and to get up very close with even the older notebooks (1440) thus adding more pixels for Retina is not worth it because it places more drain on the processor, GPU and battery. I would rather have more speed and battery life. If you have hawk eyes you might feel differently.
Both notebooks felt to be the same speed doing work even with the Retina at the highest resolution which should use more GPU resources. Yet there was no noticeable difference that I could tell so the difference in normal work is insignificant. I did not get the chance to run a heavy duty performance graphics load like X-Plane 10 but I did use Adobe's software which was on the machines as well as Apple's software.
The Retina version is, of course, lighter and thinner but I did not actually like that as it made the machine seem physically less stable and less rugged. I want a very solid physical machine. I also like the end of the line machines as they've had the kinks worked out - I'm very wary of the 1st Gen machines like the Retina. I like the heavier base of the regular MacBook Pro as it makes it set on the table better. Both were lighter than my existing much older MacBook Pro and PowerBook 15.2" notebook computers. I suppose if I was constantly traveling the little bit of saved weight might be nice but for my application of mostly working at a desk and occasionally taking the computer with me I would rather have the addition I/O and optical disk drive.
Disk access seemed the same but again I had nothing to really push it hard so I couldn't test the difference between a hard drive and SSD.
The store was noisier than my home office so I could not really compare the machine noise to my existing MacBook Pro and PowerBook. The Retina made no sound to my fingers so it is probably completely quiet. The new MacBook Pro I could feel operating which was likely the hard drive. Getting it with the SSD option would put the price about the same as the Retina and probably the same speed and sound level.
Hands on conclusion:
I would go with the MacBook Pro non-Retina because the extra Retina screen does nothing for me, is possibly a resource drain and I do want the extra traditional I/O ports and the optical disk drive which I would have to buy separately for the Retina. Having it all in one package is better. I would max out the RAM and go with the 512GB SSD in the MacBook Pro for speed, silence and hopefully lower power consumption and longer battery life. The upgrade to the 768GB SSD is not worth it to me as I would rather put that extra money towards an external networked RAID drive for reliable backup and storage which I would be able to access over WiFi using the Airport Extreme's disk ability.
I think this is an insane conclusion. I've been using the Retina MBP for over 1 week and simply can't even look at anything non-Retina anymore. Sitting down at a desk in front of my computer working at x distance the clarity is yards beyond the non-Retina junkers.