Well, my rMBP came today. I was very concerned about screen tint issues, and less worried (but still quite worried) about defects others have encountered like pressure spots, squeaky construction, sticking keys, etc. I had a terrible experience with tints on my iPad 3 and was therefore hesitant in choosing the rMBP over an MBA.
But I have been using this computer for about an hour now, and it seems great. I believe the screen has very slight tint issues (slight green tint at the bottom-middle, for example), but for me they are far less noticeable than they were on the iPad. I have encountered no other issues. I haven't noticed image retention in my regular use, and I don't plan on testing for it because I will never be able to unsee it if it is there.
This is my first Apple notebook ever (my only previous Macs were a Mac mini and a Mac Pro), and I could not be happier with it.
Time will tell whether the tints become more noticeable or annoying after extended use or if any other problems come up, but so far I am very pleased.
edit: Ran the terminal command, screen is LG.