The ABC News/WMUR/Facebook debate is half over, and the highlight was not even any zinger or flub. It was when Charles Gibson called all of the candidates — from both parties — on stage together.

As for the GOP debate itself, it actually was more informal and freewheeling, a refreshing change from previous forums as candidates sat rather than stood. At points it seemed like just about everyone was talking — making it like “The McLaughlin Group.” Gibson finally had to call a time out.

Mike Huckabee got a few jabs at Mitt Romney — and it clearly irritated the latter. When Romney asked him not to characterize his position on the Iraq war, Huckabee said, “Which one.”

McCain and Romney sparred over a Romney ad in which he characterized McCain’s past support of “amnesty” for illegal immigrants.

“You can spend your whole fortune on these attacks ads, my friend, but it’s not true,” McCain said.

But things calmed down, and there actually was some substantial discussion of immigration and national security.

And a Romney reference to “Hillarycare” inspired  a question about what the candidates thought about Barack Obama.  Rudy Giuliani: “He really doesn’t have the experience, either from the national security point of view or the executive point of view.” Fred Thompson: “Sen. Obama has adopted the position of every liberal interest group in this country.”

Huckabee also noted his differences with Obama — on issues like same sex marriage — but warned, “We better be careful as a party , if we don’t give voters something to be for and not against, we are going to lose this election.”