ESO has been a combination of disappointment and enjoyment. Disappointment that it is way too much traditional theme park MMO and not enough Elder Scrolls, and enjoyment because for a traditional MMO it does a lot of things very well, particularly immersion.
I guess I will start with the things I liked, starting with the crafting system. In many ways the Skyrim crafting system, without exploiting bugs, easily broke the game due to power creep, and using a single basic ingredient to upgrade a piece of gear was definitely in need of replacement. The crafting system in ESO is a definite improvement on these accounts. It should be noted that I never messed with cooking, alchemy, or enchanting.
Story: While there are aspects I don't care for, there was certainly a lot of good work done with writing out the story. It does do a good job of being cohesive and plays a major role in setting ESO apart from other MMO's, by minimizing the usual lackluster of kill this many of this, gather that many of that quests. A lot of thought was put into making both story and side quests each unique and with its own purpose and reason, and this goes a long way in enhancing immersion and making the MMO mechanics I hate much more palatable.
Graphics: While the limitations of modern consoles are creating major problems for gaming, it is worth mentioning that the art and animation, when compared to other MMO's is well above the norm. It is also done well in the sense of making a realistic and cohesive world, while other MMO's, even when having pretty graphics, end up being too gamy for lack of a better explanation. That is to say, its done in such a way that the world is believable as being an actual place, I can't explain why, but other MMO's I've played don't do this anywhere near as well.
Exploration: In GW2, as an example, exploration was no more than looking at the map and setting a way point for something to complete. In ESO, map exploration is much more immersive because you do not find locations without exploring manually, walking around and seeing what you find (or checking online, but thats not a game mechanic, so it doesn't count). There were several times when walking towards a quest that I would come across a dungeon of sorts and check it out for the sake of curiosity and find quests and rewards that I would not have gotten otherwise. This is a good incentive to make exploration rewarding for people who enjoy doing that, rather than feeling like a waste of time, and the detailed scenery helps.
The bad.
Combat Mechanics: There's probably several people going 'wtf? thats ESO's strong point', and if you compare it to traditional MMO's, you are entitled to your opinion. The only reason I considered getting the game was the store clerk reassuring me that it did not use tab targeting auto-attack mechanics, and he was technically right, but very wrong. The reason why I hate tab targeting isn't because I dislike target lock, it's because I want personal skill to determine weather I hit or weather I am hit, and when it comes to AOE's that part is there, but most attacks hit or miss based on manual target. What I mean is, imagine shooting something with a bow, the cross-hair is close enough to a target to highlight it but not quite in it's hit box, the arow still hits because that was determined based on whether you had a lock, not on whether or not the arrow hit its target. Another example is to side step out of the way of a slow moving spell and still be hit. Both scenarios I encountered early on and it was the beginning of my string of disappointments. And this is all very obvious when most skills cant be used without a valid target highlighted. I hate this system because it negates player reflex skill in favor of numbers, basically fights are won more by who who has the better numbers rather than on who has better dexterous control. ESO only created the illusion of being twitch (same could be said of Tera and other MMO's making this claim falsely), but it is still the old school generic MMO mechanics with just a few touch ups and gimmicks.
Storage Space: This is the reason I didn't get into 3 of the crafting skills. This game needs separate inventory for crafting, with the ability to hold a single stack of each resource without taking up actual bank space. This left me seriously regretting trying to get into crafting, as the game would have had much smoother play, and I would have had a lot more gold, if I just sold everything I didn't want and never bothered with crafting. This forced me to create two mules and use 3 characters I wasn't playing for extra storage and my bank would still be full in an hour or two prompting a very time consuming ritual of sorting it out again (thats starting with an empty bank of 110 slots), and it would take 15 to 30 minutes of logging in and out before I could play again. It seriously kills the fun.
Stat Mechanics: I didn't realize at first that ability damage was based on energy pools (magika for magic damage, stamina for physical), and finding this out (trying to figure out why my crafting character who put all points in health was so useless) was the final disappointment. It's bad enough that people even have to choose a class, but this inadvertently forces people into roles negating one huge advantage of being an Elder Scrolls game ,that freedom of choice to play how you choose without being punished for not going the stereotypical path. Case in point, I made a Khajit as a joke called 'Dances With Fleas', made her a mage making a combination of melee and mage, and what started as a joke turned into pure unadulterated fun. I would caste a slow projectile with magic, then using a 2hand ability, race it to the target and sometimes win. It was an exiting and brutal mix of magic and melee, but with the hidden stat mechanics, this character has gone from being fun to being mediocre, and at lvl 25 ish, will probably be useless if it makes it to lvl 50. The combination of being forced into a class alongside being forced to min max to a certain degree, and it is forced because the game has to be balanced at the end for the most powerful builds and experienced players. If the skill damage was based on character lvl instead or, better yet, on skill lvl, people would have the freedom we expect in an Elder Scrolls game. In the end, the whole "sure you can use any armor and any weapon with any class" becomes a bitter lie, technically you can but the game will become unplayable, and if I aint having fun, I play something else.
Story: You heard the good, and now the bad. Every person I talk to is the verbal version of TL;DR. I saw many things that hinted at an interesting story, and I wanted to know what was going on, especially when there were choices, (until I discovered that choices are too hollow and lacking in consequences to be worth caring about) but the long winded wall of text after wall of text deterred me, even with voice acting. There was one story in particular I wanted the details on and sat through a few conversations, and in the end I didn't get the details that interested me (until a cut-scene), and in spite of all the talking, no one actually said anything. I know in traditional MMO's, most people can't tell the difference between quantity and quality, but it was a shame. The stories looked interesting, and if everyone wasn't so verbose, it might have kept me playing longer. And yes, I know this review is a wall of text.
Mob Mechanics: With so many things enhancing immersion, this one thing seriously hinders it. I have quit MMO's I've checked out in the beginning by walking into a bunch of creatures who sit still waiting to be attacked in a starter zone. Thankfully ESO doesn't have noob zones of non-aggressive monsters with the sole purpose of being farmed by beginners, so it is worth noting that it is a cut above traditional MMO's. But it has a lot of the same layout in many areas, especially when coming across bloodfiends who stand there waiting for you to come within range, but otherwise standing still and drooling. Like a traditional MMO, once you figure out the aggro range of everything, it is very easy to casually walk through spawn areas without triggering anything or bothering to sneak. It is important to note that line of site comes into play, another thing ESO does better than traditional MMO's. In Skyrim, or Oblivion, it was not uncommon to walk though a clear field and get attacked out of nowhere by some critter hiding in tall grass. Traditional MMO aggro and spawn mechanics, where mobs sit still waiting to be killed or triggered by coming too close, needs done away with.
A better system is to have creatures hunt by site and sound and wander, this would also make the rare few 'kill this, collect that' missions feel more like a hunt rather than farming. This would be even better if the numbers were toned down so that the game didn't revolve around getting the highest numbers in all the land, like every other MMO, and with actual twitch combat, instead of this fake knockoff, this would be much more feasible, and creatures would maintain a fairly even level of threat no matter who fought it. For an example of this, play the souls games, even when you finally have your end game gear and maxed your preferred stats, the first monsters you fought have the potential to kill you if your careless, sure they are a lot easier, but how much of that is because you got gud and how much is because you got better numbers is unclear (or dragon age origins, where you fought to get a 0.2 increase on things, and it slowly added up, but not to the point that the first things you fought couldn't hypothetically kill you). Achieving this is difficult, but worth it, and only feasible with small numbers.
As I said in the beginning, 90% of my criticism boils down to the game being way too much traditional MMO and not enough Elder Scrolls. Maybe down the road, if I'm bored enough, I'll give it another go, since most other online games have been a hell of a lot more disappointing. Maybe what I want to see can't be done, in spite of games like Firefall, Planetside 2, and Global Agenda (each with major drawbacks) doing full FPS MMO, though I suspect the simplicity in gear and character creation is what makes a lot of those possible. Maybe what I long for MMO's to finally do, just isn't possible yet, because if any game was going to do it, ESO should have. And sorry if I myself am too verbose.