Beta tested it. It was pretty close to my expectations to an MMO ES could be. As much as we would like for better graphics, that's just not possible with the scale this MMO is going for. So equal or slightly poorer graphics would be more expected, allowing more players to play on less powerful computers. Quest lines and such were not innovative, but they sufficed to get the story going in some degree. One problem was when the quest tried to be stealth-like, and you had ten other players doing the same quest, killing everything in their path (ruining any form of stealth there was). Sound and dialogue was pleasant and not a pain to my ears. Helped promoted the feeling that you were in the surroundings, whether out on the beach, woods, caves, deserted burial ground, etc.
Everyone saying that ES should be only Single Player isn't giving this MMO a fair chance as it feels pretty polished. Not completely perfect or polished as WoW or Eve Online, but the experience isn't any worse than what SWTOR was. The biggest weakness it has, and this is a big debating point, is subscription fees. With a number of other MMOs allowing players to successful play F2P without making it feel or be P2W, it's a definite possibility that ESO could go F2P six months or a year down the road. It's almost like they're allowing subscriptions to help recoup the cost of development as soon as possible, before switching to a different payment model to attract more players.