Disclaimer: I'm just playing because of Naru-chan.
Also all "gacha" games are evil. (Although, one can earn some pretty nice cards of the highest rarity during events and such, without paying actual money, at least. Can take a heck of a lot of effort and time, though. Earning enough Diamonds to pull from the gacha is also doable. But then you'll roll over and over sometimes and get no 5-stars, too...)
Honestly the only rhythm game I've played that doesn't give me the sweats haha.

The actual rhythm game is pretty nice. The absence of distinct, visible lanes threw me off initially, but now that I'm used to it, it's really nice. It feels more intuitive and my fingers just move to where they need to be without any thought for what "lane" the "note" is in. On the other hand, the most difficult songs are harder because I haven't managed to assign my fingers to specific lanes as I generally do in other rhythm games. Most of the time I'm playing entire songs with only two fingers.
Compared with other rhythm games, this one feels somewhat on the lenient side in terms of timing.
Unfortunately, one's score is tied to which cards one uses, no matter how well one performs.
While one can fail a song, one is always permitted to finish it. Which I find is much better for practicing than games that force stop a song if one messes up too much.

The songs being original to this franchise is cool. A lot of them aren't ones I care much for, but there are some pretty nice ones. (There's sooo much corny lyrics, which are at least amusing.)
All of the songs are immediately available to all players without any need to earn/unlock/buy any, which isn't the norm in my experience.
The 3D dances in the background are neat and look good (although there are a few videos with more intense flashing lights that can be really bothersome and hard to look at. "Dancing in the Apocalypse", and some of UNDEAD's songs come to mind — the worst, for me, being "Melody in the Dark")! They can be distracting, but can also be turned off entirely and replaced with a static background. It's nice that the 3D dances can be done with any characters the player chooses. There are even a couple of songs for which the vocals change to match the characters the player selects ("BRAND NEW STARS!!" and "Walk with your smile").
All of the songs have full versions that can be heard outside the game, which I recommend for any you fancy~

The user interface is quite busy and I felt lost for a while after I started playing, with so many different currencies, learning where to use what items.

The story is available for free (some of the event stories are available only during certain times). I haven't managed to get interested in it at all, despite trying plenty of times. So, unfortunately, I can't judge it properly. Some of the characters seem charming, though. There's a lot of variance. However, most of the characters don't feel particularly realistic or relatable to me. The story is set in an alternate universe and is genuinely bizarre.
The translation is pretty good (although there are plenty of typos). The translators make a good effort to convey personality and unusual speech through use of capital letters and such. The main story is all voiced too!

One can play together with friends and be matched with strangers, which is always a nice feature. People I've played with are generally friendly. When doing Lives (playing songs) together, players can't exit or disband the group once they've entered, which is so nice compared with my multiplayer experiences in Colorful Stage of repeated disbanding late into the process (seemingly because people are being picky about which song they want to play?). Life is too short for that crap!!!
The chat function in this game is laughably (and frustratingly) bad. You aren't allowed to use curse words like "just", and "pretty". (Your guardian should have taught you better anyway.) But also sometimes you can. It's super inconsistent about which combinations of letters are "illegal". Worst of all, it won't indicate which word/letters are the problem within a message. It's pretty much impossible to guess. Rather than just using asterisks or removing the offending words, the user is barred from sending the message at all. So good luck communicating with people in-game.

This game is currently occupying 8.33 GB on my phone, which is kind of awful.

Switch, MaM, Double Face, Valkyrie, and ArashiP??? Am I allowed to do that?

so i normally don't review games on this site,but i have to review this.
if u enjoy anime,and/or rythym games,i HIGHLY reccomend this game. its such a good game.
i will say though for me personally it will lag every so often,and i will have to restart the app,meaning i lose BP. but its still such a good game. the stories and voice acting is very well done. idk about everyone,but so far for the most part the VA's from the games do the voices for the characters in the anime as well.
the songs in the game are also very well done and there are several songs that i favorited cause of how good they are.

it is a very addicting game. if u enjoy anime,and/or music based games,i would give the game a go,and try it out.

Ensemble Stars Music is a solid, rewarding game to play if:
- you like rhythm games
- you can take bad gacha rolls in stride
- you have a fair amount of idle time to play bits of it
- you can love characters a healthy amount

And it is a very bad game to play if:
- an unlucky gacha roll can be devastating
- you feel like you should often spend money on getting (or maybe getting) jpgs of anime characters
- you feel a compulsion to get the latest card of your faves
- you don't have much idle time to get the free in-game currencies/participate in events

And I am 100% serious on that. No gacha game deserves $100 for a card of your fave.