Initial impressions will wow, but as you get to the "end" of what's currently released and hit resin daily limits, the game kinda runs into a lot of grinding problems while perplexingly leaving you with not much to do (due to the resin system, since all of the good drops are basically gated behind it for meaningful equipment progression), especially if you're not in the mood to grind story aka one of the most blatant fetch quests of story telling I've ever seen in an JRPG*. So while its free and "wow its free" definitely was there initially, the game lacks content to actually be as "wow its free" later on because there's a lot of missing content the world talks about but you cannot reach. (And ten you realize that the gacha is some of the scummiest in the market, and you don't feel so good about "free" when you know this shit is designed to be predatory of others.)
The high level resin trials are also kind of a joke in that you can burn a day's worth of Resin in like 30m on trivial fights (especially in coop) and then basically cannot do anything for the rest of the day but run around grinding chests unless you use precious resources.
I'm also increasingly finding the combat to be repetitive as most weapons feel identical between units and the ultimates are about the only differentiating factor when not mindlessly autoing or triggering easy-baked elemental combos. The combat strings being so basic as a light combo (tap) and heavy autostring (hold) is extremely dull after a while, its really limiting.
*A big part of the weakness of the story, which is actually surprisingly good but is no Guardian Tales, is that it keep sending you back to the only cities available. You feel like you make no progress aside from the quests telling you made progress but you keep going in a big circle.