Too many commercials. I started giving up on the NFL after watching a punt, followed by a TV timeout, and when the game came back on, there had been a penalty on the punt, so there was a rekick, followed by another TV timeout. There is no flow to the game when there is more commercial time than playing time.
And I hate instant replay. Train your officials better.
Which is why I will never go back, even if the idiotic SJW crap stops. I have better things to do, and have rediscovered that. Four or five years ago the water cooler talk at work on Mondays was dominated by the NFL. These days I have heard virtually none. It gladdens my heart.