I have the same issues - First I thought my display is faulty - so i exchanged it and it's the same. The first phone had a more red tint and the second one is slighlty more green. On low light i can see grainy grey particles especially on white backgrounds. Looking at the facebook website, i first thought facebook is now using light textures on their backgrounds.
I'm quite dissapointed because i've been reading a dozen reviews on how great the screen is. Are people blind who are writing these reviews? A phone in this price range should not have this kind of issue...