The encounter rate in P1 is overkill and the battle take way too long for a rate this high.
This is why you play the original PSX translation, where the encounter rate is fairly *low*.
I got sort of tired of P2: EP roughly around the time you get Nate in your party. Or shortly thereafter? I was in some shopping mall dungeon. I think. I got pissed off by the stupid map completion sidequest going on since it amounted to tedious busy work. Yes, I know it was optional, but still. Also I felt there were balance issues of some sort. Namely in terms of physical attacks being *fairly* useless except in the rare case of you encountering some enemy that was null magic across the board.
I actually got tired of P3 pretty fast. It gets pretty repetitive, especially if you try to do the Velvet Room requests that come up, since way too many of them are just based around random drops. Also I really got the feeling that the choices I made in the SLink bits had no real affect. As I've mentioned before I don't think you could actually LOWER your SLink rating by being a jackass, which sort of bugged me, and, for that matter, I don't really recall any of the SLinks having an affect on eachother. It largely just led to you playing as a sort of sycophant which was really the thematic point but it rendered the gameplay less interesting than it could've been.
The game needed a sort of moral alignment thing only instead of good/neutral/evil, it should've been based on how much you developed a consistent personality and how chameleonic you were. Maybe it had this later. I don't know. I don't think it did.
Actually I think a problem you could level at most of the SMT games is that they reach a certain point where you're just calling off magic spells based on what sort of enemy data you have come up on the streen. "Oh, that enemy's weak to ice. I'll just blast it with agi."
Somehow I recall Nocturne being immune to this, as well as the DDS games. Devil Survivor actually was too, to an extent, because of how party composition worked.
P3 and SMT: SJ and I presume strange journey were really bad about this though.
I actually haven't played P1 since I was a freshman in college so it's probably terrible and I'm just runnin' off good memories. Whatevz. I do recall finding its story sort of incomprehensible.
I never had any idea what the fuck was going on in EP though. EP seems like the kind of game where you have to actually know about Japanese culture to make sense of it. Or not. I seriously remember nothing about it and I was playing it like two years ago.