I ve heard that lumia 640 has text pixelation issue.... Text appears to be pixelated with blurry diagonals while web browsing and in some apps... Is it so?
You bet it is
The devices comes out of the box with a broken and unfinished version of GDR2 that introduced this issue. I don't know if it has been fixed in the updated version of GDR2 that is currently rolling out, it didn't arrive on my phone yet. See this topic for some example screenshots: