To put it shortly: I don't dislike it, but it could be better.
0. The zone looks absolutely gorgeous. Visual artists did a great job on it after the absolute eyesore that was Gyr Abania and weather effects are all really nice.
1. The gameplay is mostly a grind, whether you grind it on mobs or NMs (which is much more pleasant), it's mostly rather one-note and there's not much to it. It's not that bad of a grind and it's not that long, but it still doesn't feel good. More on that later.
2. Culling. Oh god, the culling. It's insanely frustrating when get hit by AOEs from mobs that you couldn't see simply because they didn't draw in, when you can't react to the boss because his special effects disappear, when you can't deploy Adloqium on the members of your party because people become untargetable before you can get a cast off (and even fairy vanishes off your list). With a full instance it's honestly just unplayable.
3. Positively I should note that this is actually kind of gameplay that only MMOs can do. I like seeing people kill stuff together. I like the feeling of server-wide progression where everyone's working towards the common goal (the ever-elusive Lv20 boss NM) and how many people you've got at your level matters. Even for just lightly touching upon this kind of feeling, I'll give the instance the credit where it's due.
4. But the rewards blow. The mount and the minions are nice and all but the end-all be-all goal of reaching max level and getting your 355 weapon is simply unsatisfying for the effort. Even casual players at this point can kill normal Kefka 7 times and get their 360 weapon and 360 gear from tomes. I honestly don't know how this issue could be solved but at the release timing, a 355 weapon is just not good enough, even if it has 5 materia slots. I'm not gonna use it in the raid because I've already got a 370 one and it will beat that any day. So again... just glamour.
5. There could easily be a ton more mechanics and game systems to this. Maybe daily quests that rank from killing an assigned mob to finding a thing in the field with a hefty exp payout? What about crafting? What if gatherers could pick up some mats in the field that gatherers would then be able to turn into Eureka potions, or exp boosts. What if CULs could cook pies that give you extra points in elemental resistance? What if CRP could make a luring trap that could increase the chances of getting an NM to pop? What if BSM could make hunting traps that would stun a mob for some time so you could get past it? Why not add some kind of elemental crystals as currency that the entire server would be able to pool to spawn a monster of their choice? Why not introduce player abilities that would use energy received from mob kills as currency? A short burst of flight with wind power maybe? Or a short burst of damage with fire? Or make stairs out of ice to previously inaccessible areas? I only want to see those kind of systems because overall... I would actually love if the entire game was like this! Run around with people, kill stuff, level up, get mats and craft things to help you along the way, get abilities that let you access more areas. That sounds like MMO gameplay that would absolutely rock compared to current MSQ model of going from place to place clicking on a hotspot to watch a movie.
Oh and by the way, exchanging anemos crystals 1 by 1 is awful.