What istoryan99 said is true, Since the Galaxy S2 came out its pretty hard to find a 'flawless' screen there were various screen related issues and I experienced them in ALL 7 replacements that I had the most prominent one was the 'yellow tint' on the left side and a lot of users said its a very rare issue and accepted it as a 'normal' screen behavior but at least Samsung managed to alleviate the issue by changing the color temperature on the device to make it less visible but it really didn't resolve the issue other issues includes visible horizontal and vertical lines, most prominent in greys/whites (this issue was quite rare though), blotches on the screen when rendering greys, whiter/darker spots when rendering blacks, suction cup rings behind the screen.
Now, enter the HD SAMOLED screen from the Galaxy Nexus and Galaxy Note, it shares the same issues on the Galaxy S2 screen aside from the 'yellow tint', visible horizontal/vertical lines is the more prominent issue on the HD SAMOLED plus and a very grainy display at low brightness - true for both Note and Nexus. Video playback is broken and unacceptable when there is a need to transition from a dark shade into a full black.. to quote a well known dev:

Originally Posted by
supercurio
Hi dear Galaxy Note owners.
As many of you I'm not quite satisfied by Galaxy Note screen.
Most of the feedback reveal sub-par results, despite we all know the potential here is
huge (to say the least).
References:
-
[Q] Galaxy Note Screen Issues!!!
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[Q] Video on Note
Worst offender being shadows rendering: my diagnostic: what's supposed to be dark is not so dark.. and then boom its black (ie black clipping)
As a result color look dull, some UI elements show not quite as they're supposed to, and videos exhibit awful banding, blocking and ringing artifacts.
Here are just some of the threads that cover the SAMOLED issue:
[HOWTO] Reproduce screen issue (updated 3x results of detailed testing) some phones - xda-developers
[BUG] Vertical lines, blob, circles, pixelation on screen on some phones - xda-developers
Galaxy Nexus grainy and vertical banding screen! - xda-developers
Display problem/yellowish left side - xda-developers
[Q] Galaxy Note Screen Issues!!! - xda-developers
Horrible blue aliasing/artifacts in black areas during video playback - Android Forums
Color banding effect on the Nexus and other HD AMOLED Screens - Page 2 - Android Forums
Infact any AMOLED based screen that samsung is shipping has random issues which includes the N9, Moto Razr and PSVita.
As a user, Im not looking for perfection but a device that is supposed to be with in specifications. None of this issues existed as wide spread when I got my Samsung Wave (S8500) nor when I got my Galaxy S1. Some users may not find any of this issues on their phones so this means that Samsung is giving us a pretty random quality control, some users fail to see these issues on their phones even if its there (which is actually good since they can enjoy it).
I am really disappointed in Samsung with this and I've already lost faith in them and probably the Galaxy Note will be my last Samsung mobile phone unless they step up the quality control of their screens. Checking for screen related issues is also quite hard at the mall/store due to the ambient reflections.