When I was a kid, I played Pokemon Mystery Dungeon on my DS. I don't remember getting very far. Then Explorers came out, and I played Time version and had a much better experience up until the final part of the post-game storyline. It would be many years until I played another Mystery Dungeon game, which was... a tiny bit of Etrian Mystery Dungeon. In all of this time, I had never played a Shiren game. That changed last year when a VTuber I watch hyperfixated on Shiren and ended up getting her entire circle of Twitch into the series.
Shiren (and Mystery Dungeon in general) is a roguelike, in the sense that it's like Rogue. The term has come to encompass a broader range of games, but, some metaprogression being there aside, this is absolutely a roguelike in that you're in a tile-based dungeon environment and so on. If you've ever played something like Nethack, you'll have some idea of what to expect. And the difficulty level is pretty high, even before the real game starts once you reach the post-game (the "main quest" is pretty much a tutorial). You will most likely fail your first several runs until you manage to win by the skin of your teeth.
Thankfully, there are actually many features that will help you on your journey. At some point, for example, a monster dojo will open up, allowing you to train against the various monsters and test out discovered items at your leisure (I'd honestly compare it to the training mode you'd see in fighting games, it really is that robust). There are also unlockable items and alternate paths that can serve as shortcuts for the main dungeon. There are ways to send items in your inventory back to the warehouse at the start of the game, so if you think your run is doomed you can still save your precious sword that you've been upgrading a lot and use it on the next run. Advancing the various subplots over multiple runs can unlock characters who play a part in them as NPC allies who you might find wandering around in the dungeon (and they'll be very eager to team up with you). So on and so forth. Oh, and the rescue feature from the Pokemon games is here, too, so you can always ask your friends to save your run, or even save yourself (unless the dungeon forbids it). None of this stops the game from being a true test of your skills, though.
On that note, the story is very charming, with a twisty storyline that ended up in a place I wasn't quite expecting by the end of the post-game's story content. There's a rivalry between two pirate crews, forbidden romance, a ninja princess, and all sorts of other things. In fact, "very charming" describes so much about this game.
This is a very disorganized review, but basically, video game good.