Saw them at DL last year, one of the main reasons for me going - my first proper festival too. And to be honest, they were lazy as frakk. Came on, they played, they left. And they were OK - but that's all they were, as a show it was extremely disappointing. I watched KISS the night before, and Lost Prophets on the Sudnay - neither of whom I was really that interested in seeing but both of whom put in MASSIVE effort into getting everyone involved and 'putting in a performance' as opposed to playing your songs in a place where there happen to be people.
In fact, the guys I go to DL with instituted the 'Offspring lazy fuckwit award' which this year was won by Marilyn Manson
Great band, but no effort so not bothered about seeing them live again.
[Edit] Hey! how are these naughty swears getting through the filter?! I'm a bad bad man! lol! I do want to stress here, I really really like the offspring - I just found their short set live show as a frickin' HEADLINE ACT incredibly lazy [/EDIT]
Some people are like slinkies, completely useless but great fun to watch when you push them down the stairs.