The op3 is such a good phone but it was a Bad decision to Use a 1080p amoled panel in a 5.5 inch phone. The iPhone 6 Display looks sharper when you read Websites and apps like Facebook or Twitter. This is Not a flagship Display.
I quote the Analysis from anandtech because i can confirm this sadly
"Before covering display accuracy, I want to comment on OnePlus's use of a 1080p AMOLED panel. According to comments made by OnePlus, a 1080p display was chosen as it provides superior battery life, and because resolutions above 1080p are not useful outside of VR. I have to respectfully disagree with both points, especially because this is a PenTile AMOLED display. It has been well demonstrated that good battery life is achievable not just with 1440p AMOLED smartphones, but with 1440p LCD smartphones. While I do feel 1080p is a good resolution to choose for a 5.5" RGB LCD panel, it is simply not adequate for a PenTile AMOLED display.
When you consider the effective resolution of red and blue on the OnePlus 3, you're really dealing with a display that is roughly equivalent to the iPhone 6s in chroma resolution, except on a 5.5" display instead of a 4.7" one."