Potentially
Mild spoilers in my review

, read it at your own risk

(but don't worry, the few major spoilers are filled in black here).
I just watched the movie at the earliest hour this morning in IMAX. And as a whole, I'm pretty satisfied with this sequel! If there's something we can agree on, it's that it is not really easy at the moment to find sequels that are relevant and whose existence are actually justified by the first movie. Pixar definitively gave us a whole bunch of those “Was-it-necessary?” sequels, and to me Disney had started to follow that same path with the recent “Ralph Breaks the Internet” (although I have nothing in particular against this movie). I don't care how “good” you judge the sequel to be as a movie. Being good or okay doesn't mean it was NECESSARY (whether you like the picture or not). And every time Disney Animation Studios makes a sequel, it is one missed opportunity to have an original feature with a new universe. One more year in your life when you are given an extension to a world you already know respectful enough towards the first movie, when you could have a whole new universe made by really talented artists!... Well, lucky enough,
Frozen II definitively got a little bit of a necessity! Which is very welcomed. And to me, the real reason why it works here, is actually because, they really created another whole new world with the
magical forest, a new civilization, and new mystic places. As many of you, I was a bit afraid it wouldn't feel magic enough compared to the first movie.. but, at the end, I think it serves the movie well enough because it allows you to experiment something new.
The City of Arendelle is, let's not be afraid to say it, well.. put aside (which makes kind of a huge difference between the Frozen shorts and this sequel). You won't leave the theater having the feeling you spent a lot of time there. You probably won't even feel like there is a lot of connection between Arendelle and the Enchanted Forest except for the obvious plot devices.
So that might be one of the major positive points (or at least something it serves the movie in a way I wouldn't expected). But let's speak of the other positive points to my humble opinion:
I was craving for all the DARK elements this movie!! The more they gave us some, the more I wanted to uncover the story (you could literally make a LIST of them because of how many they are and how regularly they tend to appear throughout the movie). These feed the plot with tragedy and drama, keeping the tension up, and making you feel connected to the story until it ends. Yet talking about any of them is a spoiler.
I really felt sorry for Elsa though as she was bullied by the Nokk until the latter VERY LITERALLY INTENDS TO DROWN HER. Sure enough this will give you in good idea of what technically happened in the first movie when King Agnarr and Queen Iduna journeyed through the Dark Sea...
Actually their two daughter relive a part of their death which is kind of unsettling in rather good way
The music. I posted a message one week ago, stating that I wouldn't make a definite judgment on the songs from this new soundtrack until I witness their visual accompaniment. Well I can confirmed that those songs are there to help certain moments in the story. You'll probably be less listening to them on a loop compared to the first movie. But while watching the sequel, you'll be plenty satisfied to have them.
When I'm older is one good example of that: despite being a cute little song with a charming Broadway vibe to it, visually speaking it is also the way
you got introduced to the four spirits for the very first time in the movie including the threatening face of the Nokk... so kind of a big deal!
Kristoff's song
Lost in the Woods suddenly is shaping up like an
80's video clip! Which adds a new dimension to it ^^
I'm also really happy that the
All Is Found lullaby sung by Queen Iduna got a musical accompaniment in the final rendering (the same as in the soundtrack) for I don't remember it was so obviously present in the clip they showed us at the D23 Movies Panel.
So yeah I'm tempt to say that these songs need the video to go with it, much more than the songs from the first movie.
It's amazing how Queen Iduna looks exactly like Elsa for once specific shot 
Regarding
Show Yourself though, I was really expecting
Queen Iduna to appear almost as a ghost even for a short time maybe a bit like Mufasa in TLK.. That's a shame.
The landscapes! The landscapes are FABULOUS, it really gives you the feeling you are making a journey through Norway. Though I've never been there myself yet, it looks really like the landscapes photos you can find on the Internet, with some very mineral layouts, other very arid. It's a feast for the eyes! They really wanted to make them more realistic for the sequel.
Also, even if it might seem odd to say that for a sequel, I was pleasantly surprised by the design of the characters. And I would start with what is for the elephant in the room: young Prince Agnarr. I've never shared that with you guys but the second Frozen II trailer came out in September I've been annoyed by his design. From the one shot we got from him : he looked like a perfect dummy... Which didn't suit the adult version of the character to my opinion. Well I'm released to say that shot was the worst of him in the movie. In every another shot, the young man is pretty handsome.
And speaking of gorgeous faces and physics, let's have a quite work about Kristoff, shall we?... ^^ I kind of love how they re-worked the details of his features, and his “cuteness” as a whole. He has something very juvenile and innocent on his face, associated with the body of a mountain man. You can tell they did their best to embellish him supposedly to satisfy the fans (although this is no excuse to get rid entirely of Hans so easily! (
...expect for something that shouldn't even count..)) He has now a lot of freckles on his face! I suppooooose it is new?... Because I swear I've never noticed that in the first movie despite having watching it an hundred times..
One point everybody will notice: By the end, you will remark that the sequel follows the same paths and codes than the first movie (
Anna saving the day and saving her threatened sister, Elsa needing to be rescued after (un)intentionally putting everyone in danger, Kristoff not doing too much when you think of it...), but to be fair, knowing the journey as it is, you won't see that coming. Yes it's an obvious nod to the first movie, but you probably won't predict it until you get it! So is it a nice subtlety or just fan-service? You be the judge if it's good or bad. I think everybody will have his/her own opinion on it.
I probably need another post to talk about my potential complains with the movie ^^
But I can start with one remark. Not sure if I want to complain about it, but when it comes to the end (and having been partially spoiled about it), I was really expecting an emotionally heavier ending with
the two sisters being separated. I was expecting them not being able to see each other. I've been predicting that in order to protect the magical forest and the magical spirits, the forest had to stay secluded with Elsa taking care of the four elements on one side, and on the other side Anna assuring the well-being of Arendelle as the new leader of its people. I thought it would have been the message: to stay protected from mankind, the magical spirits had to remain hidden with the people who respect them and Elsa taking care of them as the fifth element... but no. This is definitively not what we got here. And instead, Elsa seems to be able to visit Anna whenever it pleases her. Which leaves less of a huge impact. I was even expecting that Elsa to build another ice castle beyond the Dark Sea and to become the mystical “Snow Queen” from the Hans Christian Anderson's fairy tale (only a nicer version of this figure ^^), so
Frozen III could have been a re-visiting of the original source material.
Speaking of connections with the original fairy tale, I REALLY liked the fact that
Young Iduna saving Prince Agnarr is surely a direct allusion to Kai saving Gerda!! Hats off!!
I'm not sure yet if there are plot hole with this movie... based on the logic of the story, I start thinking of it...