I forgot we already had a thread about this game!
It recently had its 1-year anniversary, just like this thread did. They've done a lot to address some of the concerns I mentioned above in the year since this game has been on the market. Most notably, they significantly reduced the time-consuming grind while still allowing you to clear content by allowing you to "sweep" a certain number of stages per day, provided you have already cleared them. Rather than taking away content by letting a bot do it, this actually adds a small additional layer of strategy/planning, since you can focus on trying to advance the level of a particular training ground while sweeping others just to get the daily rewards.
Having had more time with the game also gives us a better understanding of the summoning rates and currency distribution. And while the rates up front seem pretty bad, the overall systems make it a somewhat more forgiving gacha. There's a hidden pity rate that guarantees you'll get an SSR character in 100 summons (base summon rate is 2%). This pity counter goes across banners, so if you make 9 multipulls on one banner, then summon on a different banner a week later, your first multipull is guaranteed to be an SSR. There are also "destiny" banners where the first SSR character you draw is guaranteed to be a featured unit you don't have yet. These things combine to give free players quite a bit more control over their summons than in other gachas, where you're fully subjected to the whims of RNGesus.
I've been cutting my teeth on
"Should You Summon?" videos that give brief overviews of the characters on weekly banners over on YouTube.
Despite not being as high-earning a game as its direct competition (obviously, FEH), I'm pretty impressed that they've kept up a year of steady new content without really rehashing stuff, and it seems like there's a strong core community focused on the PvP aspect as well.