I'm a huge Persona 3 fan, it's a game that helped me get through one of the worst moments of my life. It's one of the best games I've ever played, although it was also one of the worst, both from a gameplay and pacing perspective.
With that out of the way, Persona 3 Reload tries to improve on everything that made Persona 3 great, while lessening all of its shortcomings.
Did it manage to do it? Yes. But Persona 3 was already so flawed that to completely solve its problems you'll ned to overhaul it from the ground. I consider Persona 4 or 5 the result of that, even if I don't like those games as much.
The main dungeon of the game, Tartarus, is the biggest and best glowup, while a tedium to grind on the original, now I look forward to go into Tartarus and is my favourite part of the game, It's so fun tu run into enemies and the floors feel much different from each other, at least in comparison to the original, but in the end it feels so easy even on the hardest difficulty that even if I like Tartarus you can stomp everything you encounter, it's fun but feels unbalanced and Theurgy although cool breaks the whole game, and deters from the main theme of the game about needing to rely on your partners.

The new voice actors gave it their all, I have nothing other than praise for topping and maybe even improving on what I already considered one of the best english dubs I've seen on a videogame, and the voiced social links make me want to interact with them even on the worst ones.

The biggest downgrades for me are the art and music, I can't think of a single theme that's better than its original counterpart, they all lack some spark, or strength that wasn't missing on the original. And the art direction seems a bit aimless, Tartarus doesn't seem that much outearthly now, the sprites are much more expretionless than the originals and everything looks green rather than grim.

This is not to say the developers or the direction are lazy or don't know what made the original great. On the contrary, this game feels like a love letter to the original, they are as faithful as you could be and added without compromising the characters' identities or the overall story, the episode links, except maybe Aragaki, made me like these characters even more than I already did, and spending time at night reading, watching DVDs or making coffee are also a great complement to the night activities which were lacking on the original Persona 3.

So... is it better? Yeah, it might be the definitive version and totally is the most accessible one, I don't know how I'd recommend FES or Portable above this, it's a better game and much more enjoyable.
Buuut although a better game I can't look it as an improved piece of art, the personality and edge the original had don't suit the 2020's, it's a piece of its time, and the worsened art direction and music make me look this game as a more generic art piece, Persona 3 while a bad game, was a masterpiece on its message, Reload it's a good game, but not commiting to making the mistakes the original made, such as Tartarus feeling astronomical and AI controls being mandatory among others thing I've listed, turn it into just a pretty good game