In case you didnt made it to level 10 in the beta (or was not in it). The PvP in ESO is well made.
"The last pillar in ESO's endgame is the Alliance War, which is designed with the PvP player in mind. Players of all three factions will meet in Cyrodiil (a zone roughly nine times the size of a normal map) to wrestle over keeps, resources, and bragging rights."
Massively Joystiq - Preview on PvP
PvP is completely non-instanced on one really huge map, with keeps and everything. Three realms like Daoc. I played it in the beta, and its amazing fun.