I had the screen on my 2012 15" rMBP replaced two months ago due to severe image retention. My first rev LG screen failed their test and there were no problems getting it replaced. They installed a Samsung screen. They sent it out to a service center on Friday afternoon and I had it back Monday morning.
As for the new screen, while I've only had it for two months its been fantastic. No problems to report so far. I found it to be a little warmer than the LG, but after a little calibration I was able to get it to match my preference.
I also second the option of getting Apple Care if you plan on keeping the computer for a few years. The screens aren't something you would probably want to pay full price for if something happens again down the line.
Also, this is not related to the screen at all, but I would suggest documenting the condition of your computer with the genius bar before you drop it off for repair and taking some time to look it over carefully after you pick it up. I dropped mine off in perfect condition, which they documented, but when I picked it up I didn't have time to check it over thoroughly before I left. Later in the afternoon when I used it for the first time since the repair I found that they had put five or so scratches on the bottom case right next to one of the screws. Maybe their screwdriver slipped. I thought about going back to complain, but once I left the store there's no way for me to prove that they did it, and the scratches aren't visible in regular use and don't affect the performance of the machine.
Good luck with the repair, hope you get a nice replacement screen!
