Sadly, many otherwise good games (good enough for me to recommend, anyway) have their boring parts.
In Saviors of Sapphire Wings, I just got through a massive dungeon that has no visual variety, lags a bit on my system, and is long enough to overstay its welcome (12 maps). Furthermore, it also happens to be right when you start fighting the first really dangerous monsters, like one that can instant kill and one that can hit for over 400 damage with a spell (enough to take a character from full HP to 0 in one hit); at least you can Charm them if you have a Druid. It doesn't help that most of the enemies are undead, and most weapons do poor damage to undead. Furthermore, at this point some characters can sub-class, but others are annoyingly capped at soul level 4 (5 is needed to subclass), so you can't really make use of some of your characters. To top it off, after a point rather early in the dungeon, the game takes away your ability to return to earlier areas, so if you want more visual variety or want an easier area to level up and get treasure, you can't do that at this point in the game.
(The following dungeon is also long, it seems, but at least it doesn't take away your ability to revisit earlier areas, and everyone can get their soul level high enough to sub-class, at least.)
SaGa 2 also has a dull part, where you have to go through a dungeon that has no treasure in it, which gets rather boring (especially if you're like me and have robots in your party, who can only grow by finding and equipping items).
Crosmando: For one I thought I was going to be playing an RPG not a visual novel, most of the "gameplay" is just dialogue, and it's not even important plot dialogue it's just the characters making small talk.
This is actually why I lost interest in the Final Fantasy games. Final Fantasy 6 is guilty of this, though at least the game opens up and the gameplay takes the front seat once you get the second airship; Final Fantasy 7 has the same issue, except that the game never opens up. (Chrono Trigger doesn't have that issue, but I'm reluctant to replay that game because of one part where you have to button mash to proceed, and even worse that part is between a boss fight and the next opportunity to save, so you can't even take a break and do something else; I am not going to replay that game without a (real or simulated) turbo controller because of this one part that shouldn't have been in the game.)
In some JRPGs, it often gets to a point where it feels like the conversation should be over, but there's still more dialog to wade through.
(One reason I prefer Paper Mario 64 to its sequel is that the sequel has too much dialog; the other main reason is that I actually prefer to have the reachable level/HP/FP/BP caps, since that helps guide longterm growth and keeps the player from having too much BP; also the limited quantity of each badge.)
KetobaK: Persona games are reeeeeeeeeeeealy slow, for example the first Castle in Persona 5 is like a tutorial that explains you the mechanics and it takes like 15-20hs to complete... But the game could take you arround 150hs to complete, it gets better, have interesting characters, good art design, a great story. Try I little bit more, but if you don't like it, is OK, not all the games are for everyone.
How does Persona 1 compare in this regard?