So, I got a surprise graduation present of a VITA, Mind Zero, Persona 4 Golden and Demon Gaze.
Here is my impression of Mind Zero. It clearly has inspiration from Persona, but it isn't a clone. It might not exist without Persona, in the same way RahXephon wouldn't exist without Evangelion, but it does have enough distinct elements that it can't just be classified as a clone. Mind you, it isn't as good as RahXehon is compared to Evangelion, but whatever.
Okay, so the premise is that there are two different worlds, the Inner World and the Outer World (our world). It's unclear why they're called that. The Inner World is full of MINDs, and there is a counterpart MIND for every human. But most of the time, there's no connection other than that. A MIND or a human can die just fine without affecting their counterpart. The worlds are misaligned but since the boundary is fluid, doors open occasionally and MINDs either come through and posses people, or they take people back to the Inner World to eat them, or worse. A contract with a MIND can only be made with the help of the Undertaker, who proceeds to give a vague set of instructions (pick a weapon or die, or pick a weapon and die) and who fails to explain anything in a useful manner. They actually get a lot of mileage out of that, with a big part of the game being to find out what the situation actually is and why it works that way.
Overall, I would say that Mind Zero is perfectly fine, and it stands apart enough that it's not a Persona clone. Inspired, yes, a copy, no. It's not perfect, and the battle system is a little boring, even with the double layer it has (with summoning the MINDs), but the art direction is pretty good and the music is pretty good too. (Admittedly, one of the town themes sounds a lot like some of the music from Persona 3, just without any discernible lyrics.) If it goes down in price at some point, it might be worth getting for others.