There was no talk of eating small immigrant children like there was at the GOP debate (we could cut down on illegal immigration and cut food stamps--a twofer!), but things got testy enough for Bill Richardson to deliver the best line of the night:
"I have been in hostage negotiations that have been more civil than this." In a nutshell, when Hillary Clinton attacked Barack Obama, instead of joining in, John Edwards hit her back.
It makes sense strategically, as Edwards wants this to be a two person race. And it makes sense in terms of what he has been talking about for the last four years, as his message of "change" (someone should count how many times this word is uttered during an hour of the debate) is the same as Obama's.
In any case, watch the video, as the Democrats let out their inner Giulianis and McCains...
Update: More analysis of the debate by the fantastically insightful Gottalaff

I think that Hillary Clinton's debating or performance in this campaign has little to do with her falling poll numbers and defeat in Iowa. I think that Democratic voters just finally woke up and realized that her negatives which have existed and been measured for years would seriously jeopordize her chance to win a general election against any Republican. Bottom line, for whatever reason, too many people don't like her. A Zogby poll a few months back showed Hillary would lose to every one of the top five Republican presidential contenders.
Democrats want a Democrat in the White House. Badly. Hillary is just too risky a proposition.