B-. Has not really done anything. I'm not sure how you could give him an F, he hasn't done anything that has changed the country much at all. An F would be like Iraq war or Japanese internment levels. Nothing has changed drastically since Obama. If you think Trump is an F the best you could give Obama is a D. What has he done that's so bad? I'm not a Trump fan and probably won't vote for him In 2020 but he hasn't caused any crisis.
Not doing anything bad (and even this is debatable in Trump's case) is not enough. The president is supposed to do good.
Yes I don't disagree but if not doing good is an F then what would doing bad be?