In terms of the story, I found it to be outright terrible. I think the story in this one is easily the worst to have come out of the series by far. I get that the whole story of the game is that the cast are basically making a B-movie but stuff just happens with usually very little set up. You literally go from one scrip set-up to another for the majority of the story.
And it's not even like the interactions, which is usually the staple for the series, are handled all that well either. Outside of Blanc and Neptune, everyone is so underutilized.
For one, the newcomers are completely wasted. Tamsoft for example, barely had any kind of presence. She literally just appears out of nowhere, says hi and joins near the beginning of the game, and outside of doing a single thing at the very end of the story that anyone else could have easily done...that's just about all you get of any kind of significance out of her. There are only 2 other short events (both are optional) involving her and both of which actually cover the same joke regarding her character. The interactions between Plutia, Peashy, and Uzume are basically nonexistent. Like Tamsoft, they all just join up in the second half of the game and more or less do nothing. Uzume at least introduces the final boss to the cast but Peashy and Plutia don't do anything at all. This is the first game that has Uzume meeting Plutia and Peashy and what do we get? 1 optional scene with Uzume commenting about Plutia behind her back and 1 optional scene with Uzume and Peashy basically going "yay, we both are so cool". That's it. Even Famitsu and Dengekiko got the short stick as well. They had their relationship from "Nep U" reset and got extremely flanderized even. All of their few scenes are mostly just them arguing with each other. Also, IF and Compa got the shaft yet again.
And don't even get me started on those alternative scenes you get for going into some missions with a certain pair of characters. I don't think I've ever seen alternative scenes handled so lazily in a game before. The majority of the time, the script doesn't even change. So you could get the same scene with 3 different set of characters and they all say and act the exact same way. I get it, they are reading off of a script and they are all basically reshoots but that doesn't excuse just how lazily they are handled. The characters don't get to inject their personality to change things up in the slightest. Heck, I recall there being one such scene with alternative cuts but only one of the paired characters actually shows up or says anything. The other paired character literally didn't matter despite being a requirement.
Not to mention Blanc's status as the main protagonist is also questionable. Nothing is really done with her that warrants her being the main character. I really do think they just shoved her name and image all over the game when it was already partway through development just to bank off the fact that she won the then recent popularity poll.
From a gameplay perspective, I'd say it's better overall from "Nep U" due to there being 7-ish more characters (counting normal and CPU forms separately) some existing characters getting new moves and changes, and a couple new mechanics, but starting out is made so much more tedious. For example, unlike "Nep U" where you start with everything but your specials, you actually have some of your moves and combo-strings locked out now. When you level up, you get points and you have to put them into a Technique stat (up to 10) to unlock attacks. But also note that means forgoing increasing the other three stats (HP, Pow, and Def) which are pretty important. Overall, not really an issue later on when your characters are high level and you have points to spare but I found this to be a really big hindrance to start with that lasts for quite a while. It takes so long to get enough points to unlock most of the moves. Even by the end of the story mode, my highest level character was still far from maxing out the Technique stat and that was with forgoing the other stats. So if you want to get a higher array of attacks, that means you have to basically close to cripple your character(s) stat-wise.
The selections of costumes are disappointing still. "Nep U" only had 1-2 outfits for it's characters (not counting recolors) and it's largely the same here, 1-2 outfits for everyone...despite the fact that everyone but Tamsoft got a new school uniform. The 4 main CPUs don't even get their Ultradimension outfits either. There are so many outfits for each of the characters in the series and yet it's so lacking here. Sure, the accessories are nice, but they are window dressing at best.
Going back to Peashy, Plutia, and Uzume...on top of lacking character interactions, it feels like the game doesn't want you to use them. You get them in the second half of the game and they all join at level 1. You have to spend some time grinding for them to catch up. There seems to be a lot of grinding in the game in general if you don't focus on just 3-4 characters since the enemy levels start jumping quickly between missions.
Now that I think about it, the missions in general were also pretty barebones. All of them were just kill quests with enemies that the majority of the time spawned right in front of you in a cluster. You'll usually clear them anywhere between 10 seconds to 2 minutes at most by using the Unity EXE Drive (or whatever the heck it was called). Say what you want about "Nep U" but at least it had some unique missions and had you running around some stages...but they are all exactly the same here. The game is harder but I feel for the wrong reasons. Like for example, the stronger enemies (minibosses) are far too annoying to fight. They powerarmor through most of your attacks and if you try to use a special or EXE drive on them...they get blown away usually almost immediately which will cause most of your attack to whiff. The only standout battles I can think of are the big bosses but all but one of them (that being the final boss of the story) are stuck behind the multiplayer...and even they are rather simple still.