Seeing most of other negative reviews with less than 10 hours in-game then I guess my recommendation is a 'hot take'...but here I go, I guess.
tl;dr version: most of the negatives are not caused by the game...but players' level of expectations (and reluctance to read things).

First off, people need to understand this is first and foremost a mobile F2P gacha game...so yes, progression CAN get slow.
Story is also not that bad once you go past the first 2 chapters...just like Blue Archive when everything felt silly until we get to Arisu origin and/or Rio arc.

But here's where most of the negative reviews basically came from...the power level progression.

The characters (or 'saviors' as they're called in the game) power level can be improved via level upgrade, limit breaks, skill upgrades, stellar archives (more on this later), equips (along with the usual specific sets for extra stats), and relationship level.
Not that much later on you'll also unlock a general stat & class improvements that affects all saviors as well.
There are many venues to improve your team and yes, there is also a level sync system where you just have to lvl up 4 saviors and the rest of your (select) roster can sync their levels...removing the need to lvl up everyone.

Now...stellar archives.

These are basically 'stat bundles' that are unique to each savior.
You obtain these from going through a Journey system, which is not that dissimilar to Umamusume Pretty Derby's Twinkle Series.
In each Journey you train your saviors for stats with stamina system & do quests for coins you may need along the Journey.
The base 'story' for a Journey is the same for all saviors, including the set of random events...but there are events that's specific to each savior.
Of course, that 'uniqueness' ends by the time you've made the Journey with all the saviors you currently have...but here's the thing.

There's a skip system when starting a Journey that allows you to choose between viewing all Journey events normally, skipping the ones you already viewed, or just skipping them entirely.
Moreover, there's also an Auto-Journey system...what that does is exactly as the name implies.

Also, a bit if tip if you managed to pull Bell (SSR).
When you do her Journey, don't skip her final trial battle (you can skip all trial battles with high enough stats btw) because there are extra dialogues from the MC (you) that's usually the same for any other saviors...and it ties to Bell's specific events in the Journey.

As for the 'power level hurdle' for continuing the main story, it's not that hard for F2P...because of the upgrades I stated above.
Resources for upgrades aren't that hard to obtain either.

Main story is locked by Operations progression.
Operations is the standard level stages in any other similar games...you go through 1-1 to 1-15, then 2-1 to 2-18, etc.
Boring stuff...that you can automate and speed-up while you go about do something else irl or open up a browser to watch a live stream or something.
Going though Operations also increases the amount of resources you get from idling the more Operations stages you beat.

Here's the thing though: enemy teams with similar power level can beat your team in auto.
This is probably what most people consider as a 'progression block'.
But here's the other thing though: you can actually beat higher-powered mob teams by battling manually.

Each savior has 4 skills.
Passive one that's only upgraded when you limit break by pulling dupes.
Basic skill that's pretty much the basic attack (though some saviors can have some added effects attached to it), and 2 specials.
The first special is usually a minor skill with lesser CD or a trigger skill that only activates with certain conditions.
The second special is the major skill with higher CD.

The problem with auto-battle is it'll always activate that major skill first whenever it's available except when it's a healing skill, in which it'll check the team's hp first.
Thing is, most saviors can only output their damage effectively when their minor skills are activated first.

The other problem with auto-battle is targeting.
While it does target mobs that are weak to a savior's element, it'll only focus attacks on the boss mob on a boss fight...that are often accompanied by regular mobs that can and will break & wipe your team when they combine attacks with the boss.

...what did I mean by 'break'?
Yeah, there's a break system as well along with two separate 'burst' system that gets charged differently.
Any mobs (and your saviors) have a set number of 'armor' (Toughness) to go through before they 'break', and it just means extra damage when hit in that break state...and it auto-recovers on that character's next turn.
A Burst Skill is basically the 'commander skill' and not specific to saviors, and gets charged when your saviors manage to 'break' a mob or boss.
A Burst Nova is a buff (which may vary between saviors, but mainly affects enemy's or savior's Toughness) to any of your savior's skill when activated, and only gets charged from your saviors using any of their 2 specials...basic skills can't charge it.

I still use the original saviors (Asherah, Annah, Naru, Vera) from the tutorial and still have little problem using them for PvE...and already going through lv7 Operations within 2-3 days of playing.
So unless the team's power level difference to the enemy team is obvious (like by the thousands), if your team is losing it's mainly...well, skill issue.

I do agree the UI can get confusing at first...especially if you're trying to navigate to a specific feature.
At least until you realize there's a button on top right that opens up pretty much shortcuts for everything as long as you can remember the feature's name in the game.

I Love Wedding Dress <3

It is very disappointing that the game dev chose to go down the current path which buries the small spenders and casual players. When an anniversary event was meant to celebrate with its player base and gave everyone a good enjoyment, the dev decided to make anniversary event so hard that is almost impossible to clear for casuals. Good job trying pushing your players away.