Well I had a flickering screen with occasional nano second blackout and screen tearing on occasion. At Christmas time I took it in (Before the firmware update.)
They were going to replace the screen and the cable. I was told the needed parts were not available at that time. I was aware of a firmware fix and mentioned it to them so they applied the firmware fix and I decided to take the computer home over the holidays and if the firmware fix didn't work come back in for the screen and cable. (Note: I didn't want to ship it back for a new one after reading some of the horror stories here.)
The firmware fix, did not work for me! It continued to flicker and blackout. I advised Apple of this and they said they would call me when the got the parts. (Screen & Cable.)
Today, they called as the parts were in. I took it to the local Apple store (Which is a pain, since it's in a large Mall.) Also, it was raining VERY hard.
I asked if they could do the repairs on and in & out basis. They agreed and they did the repairs in under two hours. I have it home and am tying this message on it.
So far so good! I haven't had a flicker or blackout yet. The new screen hasn't any dead pixels, yellow tinge or other problems that I'm aware of at this moment! So far so good!

(Of course I didn't have those problems with it the way it came.)
So, I'll keep an eye on the new screen and cross my fingers & toes and hope that at last I can relax and enjoy this fine computer!
I might add this is by far the best Mac I ever have worked with! I've had a few of them starting with the old box in 1986. The speed and big screen is really great!