(Some of this is from memory, and may not be perfectly accurate. Correct me where I am wrong!)
The last four years have been pretty crazy, and it's certainly true that all things considered, the US feels like it's in worse shape now than it was in 2016. But like everything else in life, Trump himself has been a mixed bag. Now that President 45 is officially out of the Oval Office, it feels like a safe time to reflect on the best and worst of the last four years; I will focus on things that were particularly good or bad under Trump, leaving out things that are always that way under any president (e.g. the US seems to still be dropping lots of bombs every year). Here's a non-exhaustive list of my personal high and low points:
Best: No new wars were started under Trump, and the US military presence in the Middle East was significantly reduced.
Worst: The Wall and other immigration restrictions. I'm all for having an orderly immigration process and I get that rules should be followed, but I want to see the process simplified and for many more people to be able to immigrate legally. Trump's goal seemed opposed to that; he wanted to crack down on illegal immigration and as a result put up lots of barriers to entry, including refugees.
Best: If you measure the US economy by stock prices, then it really was the best economy in the history of the world. I'm no expert, but likely this was due to a combination of Trump's negotiation of trade agreements, focus on US manufacturing, and tax cuts / regulation rollbacks. This does not mean that the median citizen was actually better off, but I'm sure many businesses thrived in this environment (before the pandemic, that is).
Worst: Political polarization really did get amplified during Trump's presidency, and much of the reason was him. Since the beginning, Trump has used a divide and conquer strategy that has been discussed elsewhere at length:
(1) Trump says something vaguely problematic that leaves him with a possible logical out (like calling COVID-19 "the China virus");
(2) the Left calls him out for being racist/sexist/fascist/whatever;
(3) Trump tells his supporters, "Look how crazy they are, all I meant was that the virus originated in China!" and they all support him / hate the Other Tribe more;
(4) everybody gets more polarized.
This strategy got him infinite free publicity, won him the election, built his supporter base and made them increasingly committed to him, and in a grand culmination of it all, likely led to the assault on the Capitol. His polarizing rhetoric strikes me as truly corrosive, more so than any specific thing he said--and he said some pretty bad stuff.
The increased polarization, plus Trump's recent undermining of confidence in the election process, are two things we may live with for a long time.
Best: Really impressive things happened surrounding Israel and peace in the Middle East. Israel now holds diplomatic relations with United Arab Emirates, Sudan, Morocco, and (to a lesser extent) Bahrain, with more Arab nations potentially following. You may disagree with my calling this "best" because of concerns about Palestinians, and I understand that point of view. But since living in Israel for the last three years, I would bet that the best route to a lasting peace is, well, peace, and not war. We need Israelis and Arabs living together and accepting each other more, not less. To the extent Trump had a hand in making this happen, I'm willing to give credit where it's due.
Trump also seemed to come close with North/South Korea, which would have been at least as impressive. Kim Jong-Un and Moon Jae-In met and shook hands. That's not nothing. I would love to see Biden build on this budding relationship to try to bring real lasting peace to the Korean peninsula as well.
Worst: Trump's handling of the COVID-19 pandemic was extremely bad. He denied it was a problem, then he claimed to have solved it, and now he claims the US has done so much better than other countries in terms of mortality and in terms of economic impact, all thanks to him. What he seems to have actually done was cut a pandemic early-warning system and, in large part, defer responsibility to the individual States.
In general I'm fine with States having some sovereignty over their policies, but it's different with a pandemic. If 49 states decided to do strict lockdown measures, lots of masks and testing and whatever else, but the other 1 (probably Florida...) decided not to do anything, then people who didn't think the virus was a problem would likely move--freely, across the non-border that separates US states--to that one state. And people in that one state would--freely, across the non-border--cross into the other 49, to visit family, to go to restaurants, or whatever. You can't maintain a "let a thousand flowers bloom" strategy when any one flower who defects can infect the others. The same would have been true in Europe, except that EU countries can actually close borders when they need to; this is very useful in a pandemic.
Of course, we can't blame Trump in particular for the existence of the virus, and some aspects of the mishandling don't appear to be specifically his fault; for example, the CDC screwed the pooch by telling people masks don't work and then changing their minds, and the FDA did their usual thing of delaying life-saving drugs and tests to avoid deaths of commission. But Trump could have learned lessons from East Asian countries that had COVID under control early, or he could have communicated the risk clearly and directly to convince Americans to take it seriously, or any number of hard but helpful things. But he did none of that, and the pandemic was made worse as a result.
Worst: Personally, I think one of the main jobs of a president is to be a kind and noble representative of our country to the rest of the world. On this point, Trump fails spectacularly. He is brash; he is rude; he is very uncareful with his words and repeatedly puts his foot in his mouth (intentionally or accidentally, it's hard to tell). He insults our allies and makes fun of their countries. Trump is also unpredictable, making diplomacy extremely hard because it relies so heavily on norms and agreements.
It matters, around the world. There are people in other countries who may never meet an American, whose only exposure to our country is what they see on TV. So when we elect someone like Trump, we shouldn't be surprised if they think Americans are brash, rude, insulting, unpredictable, and so on.
Some people put these things in the "pro" column for Trump, because they were sick of "politicians" who just say what everybody wants to hear. But given a choice, I'd take the fake politicians over the bull in the china shop.
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That's all I have for now; if I think of more in the next few days I will add them. Overall, with the benefit of hindsight, I stand by my decision to not vote for Trump in 2016 or in 2020.
I feel the need to point out a few omissions from my list:
1) If you feel that LGBT rights should be on the "worst" list, I feel you, but that's not something that seems uniquely bad under Trump; after all, Obama's platform in 2008 opposed gay marriage.
2) If you feel that white supremacy should be on the "worst" list, note my concerns about giving publicity to bad groups. What I have to say on this topic, I'll write separately if I write it at all. (But since things don't go without saying anymore: I hereby denounce white supremacy in the strongest terms!!)
3) If you feel that Trump enriching himself and his family through his presidential power should have been on the "worst" list... yeah, maybe. It was pretty blatant. But my impression is that this kind of thing is always going on; usually it just happens behind the scenes and out of the public eye. I guess in that sense, Trump is just another politician.
Here's hoping the next four years will be calm and uneventful. 🥂