As you know, Persona 5 was just announced:
I'm glad that Persona 5 is finally coming out, but I have a few rules for Altus to do a better job than even Persona 4:
1. Stop using the same voice actor as both the main protagonist and main antagonist. This has happened in both Persona games. P3's Protagonist and Ryoji had the same voice actor Yuri Lowenthal. P4's protagonist and Adachi had the same voice actor Johnny Yong Bosch. If I can guess your main villain just from figuring out who the voice actor is to the protagonist, then it's not fun anymore.
2. Be a little more creative with your reveal villains in both design and actions. I took one look at the Chairman in Persona 3 and instantly though: SOSUKE AIZEN. He had the personality and design that paralleled that of Soul Society's Captain Aizen. Plus he kept disappearing, "coincidently" had Aegis turn on during the Summer break, and pretended that he didn't sense Chidori even though that power did not make sense as Junpei sensed Chidori before he was captured.
Adachi was just as bad. He was basically Light Yamami without the Death Note. Adachi/Light was bored, got powers from a god, decided to entertain that god through murder, got into the middle of the investigation, kept redirecting the (P4 crew/Kira Investigation Squad) through false dropped information, and used a certain person (Namatame/Misa) to do his dirty work.
3. Have a better suspect list in Persona 5. P4 had such a bad list of suspects with that Kubo kid, Namatame and Adachi being the only prime suspects. Of course, the Kubo kid was too obvious not to be the killer. Namatame had something until the TV world came in crystal clear with Namatame's Shadow showing up, despite the P4 crew already beating that shadow and that Namatame wasn't in the TV world any more. That only left Adachi as the prime suspect and it wasn't as fun anymore.
4. Make one of the main protagonist's friends a secret villain who was working with the big reveal villain! If it worked with Kaname Tosen and Aizen in Bleach, it would definitely work in Persona 5's story. A good betrayal of one of the main characters is right up Persona's ally and would make for a unpredictable plot twist.
5. Don't over explain everything, keep up with the audience and use visual explanations instead of just making us read everything. Visual mediums like video games and movies are about showing, not telling.
For example, if you show me that Yukiko is wearing a Kimono dress when Yu meet up with her, she is featured on the TV news soon after, and the Midnight Channel shows the outline of Yukiko in a kimono dress, THEN WE KNOW IT'S YUKIKO. Don't run around it for a day or two in game.
6. No more Kooky girls like Chie for example. Chie was weakly written and her character development was treated as a side note to the more important character, Yukiko. We don't need characters like her who have little to do with the story and a remastered voice that is about as annoying as Vanille's voice was in Final Fantasy XIII. We want characters with good character development and well written backstories, not cute "silly" characters who are just there for comedic purposes.
7. Give us a proper overworld. This is a good idea to make us more enveloped in the world
8. Majorly work on the battle system to be the best turn based combat franchise in the history of Persona. A good place to start is Final Fantasy X's battle system.
That's all I can think of for now. Enjoy your wait for 2014 Persona fans!