Brightness and Contrast
The reported brightness figure doesn't seem to tally up with real-world use where the screen feels very bright at even 80 per cent. In fact we settled for 60 per cent for both brightness and contrast during everyday use.
TN panels tend to have limited viewing angles, evidenced here, and looking at it from anything other than head-on shows the image being inconsistent.
You are buying this for its FreeSync gaming attributes rather than pure image quality, reinforced by the lowly full-HD resolution.