Summary of points on how they're going to improve on stuff that's happened in P3 and P4 innocent sin? that's a dumb Persona name, it never happened.
1. The combat system will be further streamlined for better tactic control. This is not expanded on. They do say that they're improving graphics with the true HD release, but that could mean that they are improving the visuals and that's what's making combat feel fresh. And to be fair playing persona in glorious HD and with smooth as butter animations will feel awesome imo.
Streamlined is a such dirty word nowadays, but I'm going to assume it's not a bad thing in this case.
2. Like previous entries there are going to be 'themes' which connect the story. In this case it is going to be 'Take Your Heart' (in english). Could be interpreted as how someone controls/expresses their passion will be the main theme.
It's already been established in the previous Famitsu article but in more detail. You can go a few pages back for more details on the themes.
3. Stage Mechanics like those shown in the gameplay trailer will be in all dungeons. Whether there are unique ones (a la P4) hasn't been specified, but I'd wager that things like jumping and running and taking cover will be universal platforming things. This point seems to indicate that the MC is the one who traverses the stage, not the other characters.
It might just be tired gimmicks, ala Final Fantasy, where you walk up to a platform, then the character will just automatically climb it. I doubt this game will start playing Sly Cooper or something.
4. Social links influence battle somehow, but they exactly how is unspecified. They say you are encouraged to fight when you have a strong bond. EDIT: According to a friend of mine it could mean 'You fight better with friends ! :| ' or you fight better when your social links are strong. Not too informative at all.
Most likely something akin to what was in Golden