Very early impressions (after first boss/dungeon)
The Voice Acting is top notch. The initial stuff was largely okay, but once the story focused on the main group, the voice acting really started to shine. Leo's/Yosuke's delivery has been beautiful so far.
Inspirations from Persona are blatant. Nothing resembling a social link yet, but I made sure to grab a screenshot when Leo referred to the group as an investigation team.
I like the battle system. Its simple, yet has potential for some real strategic play. It is very focused on timing and balancing your skill use with defense to recoup and manage various bars of energy (MP and TP). If there was a fault to it, it'd be its pacing. I could easily see the pacing of the battles get annoying with grinding. It has auto-battling and fast forward, but it sort of stops you from using the most effective form of grinding. See, the MP is for your Persona like "MIND". When you have your MIND out, the MP takes damage instead of you. MP goes back to 100% at the beginning of each battle. So, if you summon your MIND, then you can sustain full health while grinding through weak enemies (at least this early on). You also have to manually activated each person's MIND in order to take this strategy each battle, though. I do like the battle system quite a bit so far. It feels unique and promising, but early days have a number of cracks in the armor.
I really like the general aesthetic of the game. Art is nice. Menus and other UI have a style that I really like. The battle graphics are underwhelming for the PS Vita (probably PSP level graphics), but I prefer that sort of interaction on screen over static 2D images like some games. Also, the menu is a bit slow for my liking. It looks nice, but doesn't transition smoothly between sections.
Oh, and the sound effects are as bad as people have said. I didn't think it was possible, but wow.