1. The format worked
The 90-minute debate was not the "slow and sluggish" affair that David Cameron feared it might be. The show felt less stilted and stage-managed than those in the US. It's likely that the debates will become a permanent fixture of every election from now on.
2. Brown is desperate to win over Clegg
Brown's constant love-bombing of the Lib Dem leader, "I agree with Nick", was perhaps the most significant feature of the night. As I predicted, aware that he would need Clegg's support in a hung parliament, Brown concentrated his fire on Cameron. But his attempt to sell himself as a born again constitutional reformer, after 13 years in government, failed to convince.
3. And Clegg is determined to resist
Clegg said almost nothing to challenge the perception that he is equidistant between the two main parties. He spent much of the night attacking the Labservatives and, for the most part, it worked. But it's worth noting that he was prepared to follow Brown in raising Ashcroft and that he launched a radical attack on Cameron over inheritance tax.
4. Brown can hold his own
The clunking fist didn't land the knock-out blow that some hoped for but there was no "car-crash moment". The instant reaction polls almost all put Brown a distant third but given how poor his personal ratings were to start with, that's probably no surprise. Brown seemed unusually relaxed and used the only memorable line of the night: "this is not question time, it's answer time, David."
5. Cameron could be vulnerable on foreign affairs
The Tory leader's bizarre decision to bracket China with Iran as a nuclear threat was the closest thing to a gaffe all night. As Jonathan Freedland points out, in a US debate, it would be seen as a sign that the challenger was not ready to be commander-in-chief. Brown and Clegg will be confident ahead of the Sky foreign affairs debate.
6. Brown can crack jokes (just)
The prime minister raised the only thing close to a laugh all night when he told Cameron: "you can't airbrush your policies, even if you can airbrush your posters." Given that the audience aren't allowed to do much apart from laugh, the importance of humour can't be overstated.
7. Cameron has decided to avoid personal attacks
For fear of being branded Mr Angry, Cameron eschewed the sort of personal attacks on Brown that one might have expected. As the frontrunner, his strategy was to appear calm, controlled and prime ministerial. After last night, I expect this strategy will be reviewed.
8. No one is prepared to make the positive case for immigration
Depressingly, all of the party leaders competed to see who could sound toughest on immigration. Brown and Clegg made only practical, rather than principled, objections to Cameron's plan to impose a cap.
9. Cameron is still detoxifying the Tories
Cameron's decision to begin his answer on health with a a peroration of love for the NHS proves that he's still detoxifying the Tories But Clegg soon showed him up when he pointed out: "it's easy to say we love the NHS".
10. Inequality is the great unspoken issue
The UK's vast income inequality has a negative impact on every policy issue mentioned last night. But not one of the party leaders chose to highlight it.