i've been to Fields of Rock yesterday and it was very nice. Following bands i have seen:

Opeth --> They Rock!! Only after half an hour it was enough for me.

Marilyn Manson --> He put on a spectacular show. His music is not that spectacular in my opinion

Ministry --> This concert was so fucking loud, i coulkd believe it. Nice show in a big tent.

Metallica --> they put on a great show with only old songs and two new ones.