Ruadhán Mac Cormaic, Foreign Affairs Correspondent
Was it a good debate? Any viewer expecting in-depth exchanges on the range of issues facing the next US president would have been disappointed. But that's not the point of these TV debates. As a spectacle it was enthralling. It showcased each candidate's strengths and weaknesses. Trump was uncompromising and showed his intuitive grasp of the medium by wrapping themes in pithy slogans ("stolen jobs", etc), but he was also unpleasant and vague. Clinton was calm and adroit on policy, if initially hesitant and prone to repeating pre-cooked lines.
Any surprises? We know Trump is sensitive to criticism, but I was still surprised by the ease with which Clinton was able to goad him. Time and again – on his taxes, his companies' discriminatory rental policies and Birtherism – Trump took his opponent's bait. A cannier debater would have known better.
Key moment? Trump appeared to admit he hadn't paid income tax, then tried to make a virtue of it. One candidate in effect called her opponent a racist. In another election year, these would be key moments. In 2016 they're par for the course.
Who won, and why? Hillary Clinton won, but that probably won't damage Trump. The evidence suggests debates have a limited impact on voting. And Trump did enough, particularly on jobs and trade, to cheer his own supporters.
Noel Whelan, columnist
Was it a good debate? Ninety minutes is a long time in television and it is an eternity in politics. This was a good debate because it served it functions. It tested the candidates' knowledge of the issues, it challenged their capacity to articulate ideas and – because it lasted an hour and a half – it exposed their true temperament. Trump fell well short of the presidential standard on all these aspects. Clinton passed with flying colours.
Any surprises? The only surprise was that Trump was initially subdued. For the first 20 minutes he was a calmer more measured Donald then we have seen on the stump or in the primary debates. His arguments on jobs and trade even if inelegantly put will have resonated strongly with his target audience.
Key moment? The key moment came about half an hour in, when Clinton destroyed Trump on his failure to publish his tax return. She suggested they would reveal that he "may not be as rich as he claims to be" or "is not a charitable as he claim to be" or more damaging still that he had not paid any federal taxes. She tore into his claim to business competence asking "What is his hiding? Who does he owe money to?" Shortly afterwards, Clinton pounded Trump on the "racist birther lie" he had perpetrated for years, suggesting President Obama was not born in the US. From then on Clinton owned and dominated the debate and nailed her claim to the office.
Who won? Clinton won hands down. Precedent suggests that debates can determine US presidential elections. Even in this unprecedented election campaign this clear victory will help Hillary greatly.
Una Mullally, columnist
Was it a good debate? Equal parts fascinating and frustrating.
Any surprises? Trump's strong start, compared to Clinton's stilted, flat and seemingly nervous beginnings. Until halfway through the debate, he had the upper hand. Trump was more free-flowing and passionate, even if a lot of what he says can be vague and nonsensical.
Key moment? "Donald just criticised me for preparing for this debate. You know what else I prepared for? Being president." – Hillary Clinton
Who won, and why? Trump is an entertainer, and difficult to debate considering his tendency to favour speaking in a scatter-dash and rambling manner. Clinton certainly appeared more presidential, but not exactly inspiring. Trump focussed on himself and his prowess as a businessman. As the debate wore on, he faltered. Clinton dealt killer blows to Trump on his failure to disclose tax returns, being sued by the US justice department, his involvement in the ridiculous birther movement, on race, and his "cavalier attitude" when it comes to nuclear weapons. Trump's answers and statements grew poorer as the debate progressed. In the final minutes, Clinton almost mocked Trump's assertion that she doesn't have stamina, and brought up his deplorable record of sexism. Trump unravelled, Clinton won.
Chris Dooley, Foreign Editor
Was it a good debate? It was compelling from start to finish but it was too one-sided to say it was a good debate. It was substance versus bluster right from the start, with very little serious engagement or exploration of alternative policies.
Any surprises? I thought Trump would come better prepared. A big question beforehand was: how will he stand up to the intense pressure of a 90-minute debate? Will he crack before it's over? But he was in trouble from the opening minutes and it got worse for him as the debate progressed. He was quoted as saying he had prepared by "playing golf and eating cheeseburgers"; it looked like it.
Key moment? Several to choose from as Clinton scored point after point. Her enumeration of the small business people who had been "stiffed" by Trump was one of the major blows she struck, particularly as Trump didn't even deny it.
Who won, and why? Clinton won every segment and on every level. She began on the front foot, setting out her economic plans in positive terms, while he moaned about foreigners "stealing our companies and stealing our jobs". That message of his might resonate with large sections of the US audience, but he never moved beyond such sweeping generalities. He was even weaker when the discussion turned to security and race relations. She was also measured and in control throughout, whereas he constantly interrupted her and struggled to keep his temper under control.
Damian Cullen, Assistant News Editor
Was it a good debate? Definitely. In a 90-minute debate between two people, without any break, there are no hiding places. Host Lester Holt did a great job, only interrupting occasionally to bring the candidates back to the topic – apart from one occasion when he probably shouldn't have continued to argue with Trump over support for the Iraq War.
Any surprises? Trump was negative from the first sentence, which I didn't think he would be. But then, maybe it was naive to think he wouldn't start a debate the way he's started every campaign event in the last 12 months. Trump also surprisingly missed several chances to put Clinton on the back foot – fluffing his lines on the emails controversy. Did he even mention Benghazi?
Key moment? "He has a long record in engaging in racist behaviour." No messing with that comment from Clinton. It was stinging. A close second was the democratic presidential nominee's attack on Trump for "stiffing" many people who he employed.
Who won, and why? Clinton looked prepared, Trump didn't. QED.
The strategy, if it was one, to keep Trump as “off the cuff” as he was during the primary season was a mistake. A 400lb one.
David McKechnie, Deputy Foreign Editor
Was it a good debate? Good in that candidates lived up to expectations and duel was engrossing; not so good in how unevenly matched they were in debating terms, mostly due to Trump's failings on detail. Some of his answers (his property deals, position on Iraq) were rambling and incoherent. Moments of high entertainment, like the image he evoked of a 400lb American sitting on his bed hacking into servers. Split-screen format was compelling.
Any surprises? How Trumpian Trump was. Not just poorly prepared, fidgety and long-winded, but also how brazen he was when attacked on tax and business practice. "That makes me smart," he said when accused of not paying taxes. On taking advantage of the housing crisis: "That's called business." A mild surprise that Clinton came across as more robust - format underscored her mental agility and calm body language. He often looked frustrated and exhausted when she spoke.
Key moment? Clinton using the term "racist" on Trump and the birther controversy. It drove home the bizarreness of the birther issue, and echoed back to Trump's poor earlier responses on stop-and-search and discrimination accusations in the 1970s. A reminder of how badly he is faring with minority voters and how little hope he has of changing that.
Who won and why? Clinton by a mile - calmer, coherent, patient. Good on detail, well-prepared put-downs and humour that was lightly dismissive. Could have done with some plainness and simplicity in her message, but ought to have swayed some neutrals. In the eyes of his supporters Trump probably did just fine.
Kathleen Harris, video journalist
Was it a good debate? In a very fiery first debate, Donald Trump aggressively attacked Hillary Clinton over trade, emails and Islamic State, while Clinton focused on portraying Trump as unqualified and short on facts.
Any surprises? Though there were moments she appealed to "fact checkers" rather than making rebuttals, Clinton came off as poised and capable, lightly touching on a number of policy areas that Trump avoided.
Key moment? The standout moment came near the end: when Trump claimed Clinton didn't have the "stamina" needed to be president – a dig at her recent health problems. Clinton coolly responded: "As soon as he travels to 112 countries and negotiates a peace deal, a cease fire, a release of dissidents . . . he can talk to me about stamina."
Who won and why? The retort, a succinct summation of her experience, drew a cheer from the crowd. If she hadn't won already, this is where Clinton bagged it. Convincing undecided voters that he has the temperament to be president is one of the main challenges facing Trump in these final weeks; he's unlikely to have swayed many after tonight's erratic performance, which included several interruptions and clumsy deflections. Though he started strong, Trump weakened when asked about releasing his tax returns, which forced him into the defensive, and eventually crumpled when moderator Lester Holt pressed him on birtherism.