Opinion: Persona 5 will be a better game than Final Fantasy 15
I call it as I see it.
Action Based Combat.
Final Fantasy 15 is going with a seamless world, and that includes the battle system. An Action-RPG battle system is something Square Enix has done pretty well before with Kingdom Hearts and even Type-0. When it's done right, it adds far more depth to a game, but there's also more room for error. SE has shown they can make ARPG systems that work in much smaller games, with less technical issues and limitations that were easier to work around. Trying to seamlessly implement this battle system in a larger, denser, and more varied world brings a ton of complexities to the table, that I'm not sure SE will overcome.
First and foremost is the camera, which took a hit in the newer Platinum Demo, often going crazy around objects and jerking about. Then, you have to worry about character controls during battle, and let's just say that the Platinum Demo shows SE is not quite Platinum Games when it comes to smooth combat and smart button placement. Finally, we can't forget about AI either: The AI controlled party members in Episode Duscae were often more hindrance that help.
You may argue that my critiques for some of those elements are subjective. After all, you may enjoy the control changes between Episode Duscae and Platinum Demo. Here's something that's not up for debate though: Frame rates are more important for these types of battles systems, and both Final Fantasy 15 demos become more like choppy slide shows than video games whenever you have a significant number of enemies or effects on screen at once, and it affects combat greatly.
Well timed perfect dodges, counters, and chain attacks are hard to nail when the game starts to slog about. In an attempt to combat dropped frames, SE dropped the resolution to 1600x900 on PS4 for Episode Duscae, and opted to use a dynamic resolution for Platinum Demo. It's a smart move, but not one that has really fixed frame rate issues, even with smaller groups of enemies and a solo protagonist. Unless you're somehow happy with cheap shots in battle because the console is shitting the bed trying to keep up with SE's ambition, it's an actual issue.