So I'll preface this as saying that I finally decided to register (and stop lurking) after reading through this entire topic. I didn't have any experience with the Reborn online league, and have only been playing this game since Episode 14, but each episode since has elicited a replay from the very beginning.
There's a lot of things the game does well—better the official games, even—so this is not really a criticism of the game itself. But as it's a topic on what you don't like, I figure I'll expound on them here.
- As mentioned several times, the game gets rather tedious with the sheer amount of backtracking, especially through the city.
There could be a better sense of direction through the game. And while the wards are cool enough in design, navigating through them more than a few times just feels like a waste of time. I almost always just speed through them on my bike at 3x gamespeed. Backtracking through a city is expected, especially if you're a completionist like me, but when you're skipping through the city many times over, it really loses a lot of the appeal.
- There's a severe tedium to a lot of the puzzles.
A few of them are very well designed, but most of them are just grindfests in high encounter zones (Chrysolia, 'Mt. Doom', the Water Treatment Facility, push the crustles, and electrical-floor conveyer-belt meteor base come to mind). They aren't terribly difficult as puzzlers, but they're just long and often require going back to the same spot over and over again. These kinds of engagements get old, particularly on replays, because they don't explore anywhere new and your progress doesn't feel as tangible since your environment stays the same. Add in the high encounter rate in this game and it's either just a tax on your repels or your patience.
- Characters sometimes become rather one-dimensional.
Not necessarily that they are one-dimensional, per se, but they're often portrayed that way. And I would liken it to the worst bits of Game of Thrones writing where they essentially zone in one trait of a character and beat us over the head with it in every scene they're in (almost like reminding us that that's who they are, in case we forgot). It's how Fern will always have some way of calling you a loser, even when it makes no sense. Or how you can grow tired of Bennett by the third time he shows up the screen even if you can kind of see where he gets it. There's just so much "enough already, I get it" in the handling of characters. It seems like every character is reduced to their shtick.
- Railroading of your character
I get sometimes that moving the story along is necessary, and as a game designer you can't simply allow the player too much freedom or you create a nightmare number of scenarios. But no one likes feeling like they're set up for failure no matter what they do. But the way the protagonist is handled sometimes is really immersion-breaking. I get that, as an RPG, you often want to allow the player the freedom of creating their own character (sprite, style, etc), and as such you want to keep them relatively silent so you can imagine them however you like.
But in this scenario, the last thing you want to do is force player action (or often player mistake) as a means of story progression. You take this character where you work so hard to preserve optionality and make sure they're open ended enough to fit the RP creation of a wide variety of players, but then force them to do a variety of questionable or dumb things just to advance the story.
Like why are you forced to fall into the Nuzleaf trap, even if you can clearly see that it's a trap? Why are you forced to 'read' (even though this was changed in E16 it still feels like you're forced to read it) Titania's diary to advance the plot to the Water Treatment Center? Why, if the gems are so valuable, are they filched off your character by every other character you encounter? Why isn't your, presumably reasonably intelligent, protagonist protecting these vitally important gems better? Why aren't they hidden under layers of clothing and tied to your person? Why aren't they tucked deep in your shoe/sock? Why aren't they in some carefully zipped inside pocket of your bag? Why aren't they shoved up your rectum?
There's a degree of presumed/forced incompetence about your character that makes it feel like you're set up for failure regardless of your RP preferences. Which is fine; your character can be a bit of a bumbler. But if that's canon, you might as well create a set protagonist and develop meaningful relationships/dialogue with various characters you encounter.