I really hope that there weren't many burgeoning conservatives hearing Donald Trump speak for the first time, but I'm not sure how likely that is. For everyone else he's a known quantity. His performance was more or less like his historical performances although for Trump it was probably the worst he's ever performed while being more vulnerable than he ever has been (which could only have been irrelevant in this context). His base liked it, everyone else thinks he's a psycho, and Republican voters are just going to vote for the Republican regardless.
I'm seeing a lot of people upset that the moderators didn't do a better job debating Donald Trump. Joe Biden was supposed to debate Donald Trump, and he was not up to the task. He rebutted many of Trump's lies and said many things that would probably have been effective if he had the energy he had even 4 years ago, but it didn't matter because he could hardly get words out and looked terrified most of the time. Worse still, many of the things he did say which were understandable were word salad (contrasted to Trump who speaks so fluently in word salad his base doesn't notice). The thing is though, most democrats already knew Biden was this bad and are deliberately obfuscating to others and perhaps even themselves this fact even now. No one who was going to vote against Trump is going to change their vote just because it got way more difficult to be dishonest about the Joe Biden's abilities for 90 minutes. Biden is really irrelevant to this election anyway, it's still about whether or not we want Trump in office.
What seems to me was most relevant about this debate is that we have reached a new low which is strikingly obvious to everyone paying attention who isn't pursuing their political party's interests above even their own. We have never had a debate which was almost totally unintelligible from beginning to end like this one was. I can't guess what the effect of that might be.