Whoo I can finally participate in this thread.
First Persona game I've really played (didn't get past the P4G intro sections, and I played a decent amount of Dancing All Night but don't think that counts
) and tl;dr it was a delight.
Unfortunately my game timer is off because I spent a lot of the game playing on Vita in chunks (what a lifesaver -- P5 is now by far my most-played Vita game after owning the system since launch) so there was a decent amount of standby time, but I probably poured ~80 hours into clearing the game. I actually didn't use any guides other than to get the confidant answers (which felt justified given how bad the translation was in parts) and the fusion calculator (though I only wound up using it just to finish the Twin Wardens challenges -- otherwise most of my fusing was just "oh neat, I can make this higher-level Persona, k here we go!") and the game felt incredibly exciting partly because I really never knew what I was in for.
Ultimately the aesthetics of the game were really what put it over the top. Put some grimdark generic fantasy adventure in place of this, and I probably would have bailed five hours in. But the style of the game got me hooked and kept me going through the early levels, and then all the social stuff and fascinating mechanics like fusions carried me into hours 40+ easily. In the non-spoiler threads, I saw people often mention that most of the palaces were too long, but I really didn't feel this way at all until the ship. The mouse parts and just constantly running through really similar enemies there were the first time anything felt tedious to me. I actually grinded like absolute nuts throughout the game (like FFX way back in the day there was just something about the game that made me want to grind and made grinding quite fun and relaxing) so nothing was every really a significant challenge for me (I did die a couple times, but didn't have to come up with crazy builds ever or anything) but the combat was still always engaging except when my levels really got out of sync with what was happening in Mementos, but even then once you get Futaba leveled up Mementos is pretty easy to blitz through (ahhh, all the grinding I did there).
Social aspects were definitely a game-changer in terms of making the game interesting beyond just combat and story progression. I love the idea, though I do almost wish they had different minigames or something instead of just dialogue selection but I'm probably just getting greedy.
Some minor parts of the story were a touch corny, though when I felt something was off I usually chalked it up to the bad translation. I actually thought most of the EN voice actors were great though (except maybe Sae and probably a couple other minor characters I'm forgetting), even if their lines weren't always the best. Actually considering doing a NG+ even though I rarely even beat games this long anymore, much less NG+ them just to max out the last few confidants I missed (due to my non-cheating I didn't realize Sun persona couldn't be advanced after November -- d'oh!) and just to have another quick romp through everything. I don't know if they'll do a P5G, Dancing All Night, or a painting game with Yusuke or whatever but I'd definitely be up for another game with the cast.