So far, for me at level 21 Sorc, Daggerfall Covenant, this has been an extremely positive experience. I find the game quite immersive, with the best things about it so far being the questing and the combat system.
The questing system in this game is the best set-out of any MMO I've every played (except perhaps TSW, which offers a fantastic single-player questing experience too). There's something about the flow and pacing of it all that's incredibly congenial to me, and gives me a sense of deep immersion in the game world - as opposed to a feeling that I'm just running around pulling quest dispenser levers and racking up some measurement.
It UI minimalism actually helps very much in this regard - the game conspires to focus you down to the task ahead of you in the virtual world, instead of drawing your attention to numbers, to all the meta stuff. I can see how this might be frustrating for some, but that's what addons are for. I think the devs were right to offer the player a sort of "base" level from which to experience the game, and for that to be an immersive single-player questing game.
It did take a bit of getting used to, because the trend in recent years has been to have lots of flash, lots of bling and ding, lots of hand-holding, and this game doesn't do that sort of thing. This game seems to want to give you a more "realistic" experience, with a slower sort of pace.
The MMO experience can tend to get frantic, and it's easier to take on a sort of lab rat mentality, where you're focussed on some achievement or other. This game seems to want you to be more immersed in the virtual world itself, and to really have the feeling of being an adventurer wandering through a magic-filled, often grim realm. And I think it succeeds very well in that.
At the end of the day, as with the single-player TES games, the real star of the show is the lore, and how it forms a semi-solid imaginative backdrop to one's play.
To put it another way, fantasy-themed game worlds are often perfunctory and "thin"; TES is rare in having a very old-skool, rich, worked-out fantasy-themed world to play in.
Question is though, is that enough? Is it enough for a game these days to offer immersion in spades? I fear the game isn't going to last in its present form for very long - I fear that it's going to have systems altered and systems put in to make it more of a vanilla, e-sporty, Bartle "Achiever"'s type of experience as time goes on. I fear that it will eventually go f2p, and be slathered in stuff that psychologically takes you out of the game world.
But hell, I'm having fun right now, and can see myself continuing to have fun for a few more weeks at the very least.