I enjoyed the Trivium set alot more then the Amon Amarth. Some of the stuff from Amon Amarth was good but their sound was not cutting it. I watched one of the guitarist do a solo, but I couldnt hear it. On their last song "Fire" something, they have a part where the guitarist just does hammers + pulloffs for 2 minutes. Trivium has more potential then Amon Amarth to be creative musicians. Their songs are put together much better and their solos blow Amon Amarth's out of the water. Plus their singer is alot more talented then Amon Amarth's. His vocal range goes alot further then just screaming/growling.
However, Trivium's leadman needs to take his ego down a few notchs and take these types of situations more mature. And for whoever said he was too demanding and telling you to get into circlepits, thats the whole point of having bands play before the main event. They get the crowd wound up and ready to fucking headbang/mosh/whatever. I think he did a good job on getting us pumped to see Bodom.