Been checking this out with a few friends, playing my own lowbie plus having borrowed a lvl 50.
I have to say that it feels a lot like DAoC's PvP — which was RvR really, realm versus realm — feels good, fun, the endgame is in the RvR = best endgame. At least it was in Dark Age of Camelot.
Not saying this MMO is perfect or anything, but if you're interested in PvP, which matters and has an objective, something persistent where you can make a difference with your clan, where tactics actually matter in organizing raids on each others strongholds, then ESO would definitely be my pick.
Plus it seems to run great, lag is minimal, FPS is good on ultra settings even with a hundred people in combat, some D/C issues but limited.
It's funny because people have prior to release been putting down ESO the most, and hyping for example Wildstar, yet now ESO seems to be by far the best game of them all, and the one with the proper gameplay (unless you're into to solely PvE of course).