Aside from the mischaracterizations and untruths spouted by Joe (plenty of time to address those later), some thoughts:

1. Why did Lieberman feel the need to talk over and interrupt Ned the entire debate? The arrogance constantly emanating from the right-hand side of the screen was really a little much, even for Joe. Check out some of these comments from viewers at NBC30's website (hat tip to Eric):

"Every time Senator Lieberman chose to interrupt the debate and shout over Mr. Lamont, I was reminded what the real problem is... the Senator refuses to listen to Democrats, to our questions, to our answers, and our advice." - katgw

"(Senator Lieberman) seemed overly defensive (almost scared), was somewhat "disrespectful" in continuing to talk through the rebuttals and not let Ned speak (not the word I really want, but close enough), and appeared to just be a grumpy old man. Maybe we don't fully know Lamont after this debate, but I sure learned a lot of Lieberman. And I don't think I like it." - easelmmc

"I thought that Ned came across like a real person while Joe seemed liked the entitled DC Aristocrat. Joe's bullying tactics only fortified the opinion I had before watching the debate." - EnricoM

2. It's obvious Joe doesn't care about winning over Democrats, or about the August primary. He mentioned Schlesinger multiple times tonight, recycled a tired Reagan line, and staunchly defended his support of earmarks, the Bush-Cheney Iraq policy, and the Bush-Cheney energy policy. He's aiming for November, but he'll surely use the rest of July and August to spend his millions on negative ads against Ned.

3. Ned's last few lines about Weicker were great. Lieberman had no answer for them.

4. Joe kept on asking "Who is Ned Lamont?" throughout the debate, trying to run away from his own 18-year record. But I think Connecticut has a much better idea of who Ned is tonight. And that's not good news for Joe.

5. Compare the Joe in this debate - angry, arrogant, attacking Joe - with the 2000 VP debate vs. Cheney - agreeable, docile, timid Joe. And tell me which you thought was for a senate primary and which one was a presidential general election. Why is Joe more angry at Ned Lamont than he was at Dick Cheney?

Update: At MSNBC, Bob Shrum, Tom Curry, and Ned himself seem to all agree:

Shrum: "I wish Joe Lieberman had been this aggressive against Dick Cheney in 2000. It may not work in a Democratic primary, but it would've worked in that general election."

When I said the tone seemed quite different from the 2000 debate Lieberman had with vice presidential candidate Dick Cheney, Lamont, seeming somewhat abashed, remarked, "That's what I should have said!" -- meaning he should have said it during the debate.

Lamont added, "When it's debating a Republican, it's like a tea party," but "when he's debating a Democrat he shows his passionate juices."