I had such low expectation for ESO PvE content mainly because I had horrible beta experience involving "logging off at lvl3 on newbie island and never bother to log back on". But hey, I am lvl30 now on live and after finishing everything in 3 main maps (plus 2 islands), I have to say this whole ESO MMO experience has been rare, interesting, and surprisingly positive.
So what happened?
Exploration, you get quests by explore. Yes, there is a main quest line to follow starting from tutorial area. But once you finish tutorial zone. You will be at the main city. You can choose to go back to the "beta newbie island". It's up to you, but all I know is from the main city, every direction you explore, you will find side quests for all these little areas. Keep in mind that explore an area doesn't always mean finishing quest line there.
In many cases, there is quest available for an area. Instead, you need to visit a shrine; defeat a group+ mob; close a rift (AKA dark anchor); or discovery ancient craft station in which to craft unique gear set. What's more? You find all crafting materials only by exploration; you will find Lore books that level up your skills, even better, if you love lore in Elder Scroll. READ ALL OF THEM. What about chest? You will find all these hidden chests out of nowhere and have a little lock-picking mini-game. Get into someone's house? open every closets, desks, and bookshelf. It is like Christmas, different stuff every time.
And boys, you don't want to miss out all those Skyshards. That's how you get more skill points. You can also join up Fighter Guild or Mage Guild just like all other Elder Scroll games. By leveling up these guilds, you can acquire unique guild spells/abilities. And don't forget you can turn in Vampire or Werewolf!
Questing in ESO does NOT get overwhelming or distracted. Single quest chain for each small area, you don't grab five quests from five different NPCs in a hub like you shop in a supermarket. Instead, you can spend time and listen to voice acting from that SINGLE quest chain in the area. Even better, I have NOT encountered a single quest that involve "kill X amount of mob". None of that shit. And no, quest giver does NOT shown on the map, you could only detect them through compass.
Now, that's just PvE in ESO. AvA(massive PvP) is even more exciting in ESO. Remember RvR in DAoC? Warhammer Online? Or WvW in GW2?