Yes, I was at Hyde Park too and they were ace.
I thought Serpico were awful, though I do dislike Avenged Sevenfold which seemed the nearest reference point. One minute they seemed to want to be Metallica, the next Green Day and the mix didn't work for me. Stage presence was poor too. Singer didn't seem to know what to do with himself when not singing and rest of band rooted to spot. I guess you could say I didn't like them.