>>>Spoilers below, of course, but they're pretty minor<<<

I recently finished Persona 4 Golden, and I enjoyed it so much that I'm deep into a second playthrough (110 hours and counting).  I applaud Atlus for its unconventional design choices, e.g., putting responsibility for solving the mystery on you instead of feeding you the answer; allowing you to enjoy peaceful days after you've well and truly solved the case and saved the world; setting an attractive contrast between drab, foggy Inaba and the brightly colored UI.

But what Persona 4 does right is pretty well settled.  I think it would be more interesting to discuss where Persona 4 stumbles, especially in comparison to Persona 3.

The pacing is just terrible.

The idea of Persona 3 is that you need to juggle your various responsibilities -- to school, to your friends, to SEES -- and find a balance among them, and the game is structured in support of this idea: Over the course of one or two play sessions, you get a bit of daily school and afterschool life, a bit of interaction with the central cast, a bit of story, and a bit of Tartarus.

Persona 4 has no balance at all among these things; some fight for dominance and settle in for a while, while others are dormant for much of the game.  Events like the visit to Tatsumi Port Island and the Culture Festival are very funny, well-written, and well-acted, but they just drag on too long and break the flow of the game.  An afternoon in the TV world can last forever, since there's no fatigue mechanism, and the fox is there to act as innkeeper.  And the game is very stingy in revealing the murder mystery that serves as the backbone of the story until it unfolds all at once in the December climax.

There's too much of everything.

Rather than an RPG with some elements of a dating sim and of a slice-of-life anime, Persona 4 is all of these things in full.  And the game leaves nothing unshown or unsaid.  Persona 3 is full of vignettes that give you glimpses into the characters' personalities and lives, based on which I can imagine that they have lives apart from their relationship with the player character and from SEES.  Persona 4 doesn't leave many gaps for my imagination to fill.

The lack of conflict among the central characters is boring.

This one is pretty self explanatory.  The characters get along famously with one another and all want to be your best friend.  At times, they overtly compete for your attention.  This denies the chance for relationships to evolve, apart from simply going from close to closer.  And having the relationships border on idolatry makes them seem false.

At times, the inseparability of the characters is comical, such as when you hang out with Marie, and you serendipitously run into not one, not two, but all seven of your teammates.

Having characters face their suppressed selves early on leaves little room for later character development.

Later character development occurs almost exclusively in social link interactions and is generally limited to characters continuing to come to terms with their other selves.  Since you've already seen the sides of them that they most wanted to remain hidden, nothing significant about their personalities is left to reveal.

I don't know about you (actually, I do, seeing as how you've already stated your opinion), but those side events, I actually really appreciated how they lasted for an hour or two, because after slugging through each dungeon, I wanted a friggin' reward, and those scenarios didn't disappoint.