IMO Trump did slightly better than Biden.
Positives for Biden: He tried to stay on point, and I believe he did much better than the last Debate. I think because his handlers had a good grasp of what to expect and they had most of Biden's talking points written down for him. (You could see him glancing and shuffling pages from time to time.)
He also seemed a bit more lucid and energetic than previously. His strongest position was on health care, IMO because that's something he was involved in back during the Obama years, so it is something he can excel on. The next strongest was on Trump's tax returns, a sore point needing an answer for years.
Biden's Negatives? He really had no valid responses to why, after being in office for 8 years previously, he (and Obama) could not get any of the things he claimed to support done. I know he tried to blame it on the Republican controlled house. But as with Trump, Obama controlled both houses the first 2 years and that's how they got the ACA through in the first place. He was also weak in his responses to Immigration issues, Energy, jobs, and his own unclear "Covid-19 plan." It left us to believe he would take draconian measures that would destroy the economy.
Trump's Negatives: Healthcare was one of Trump's negatives. It was also a fairly weak response to concerns about how to provide healthcare coverage for those in need which is a major issue with many voters who depend on it.
He was clearly shooting from the hip for the most part throughout the debate and was not as prepared to respond to certain questions as a result. He often shifted direction and did not directly answer some questions also as a result.
Trump's Positives: He hammered Biden on his own "corruption;" as well as his energy policy; lack of an actual "Covid-19 Plan," (as in one that did not involve destroying the economy); his prior poor history on foreign affairs successes; Immigration faux pas; and his falsehoods about Fracking and Energy positions. He also reversed Biden's demand Trump show how successful he was in 3.5 years by citing the economy, foreign affairs, and the fact that even with Democrat Opposition he did better on helping minority colleges, freeing prisoners, opportunity zones, and many other improvements.
IMO Trump won this debate doing a bit better than the first one. Biden lost by a larger margin, but it did not necessarily knock him out.