They're amazing live!
I've seen them twice this past year and they're definitely one of my favourite bands live. They're tight on stage, entertaining, rock like a bastard and are heavier live than on the CD's.
One thing I will say though, is that when Dave Grohl took the drums for one song during the show I couldn't look anywhere else, and I'm normally a guitar girl. His playing is out of this world, so maybe it does have something to do with his personal magnetism?
Whatever it is, it works and I recommend anyone to go and see them if you get the chance