Different genre. Same quality Persona-verse writing
So yes, the fighting mechanics are solid. The game looks pretty and combat can get satisfyingly complex. A lot of work went into making the game flashy, and I loved it. But more importantly, I was wrong about the story and atmosphere. For starters, yes, the game -was- canon. And secondly, it wasn't half-arsed. This was standard quality Atlus writing. Nothing was rushed or pooped-out; the humor is there, the nuances are all there, and everything felt legitimate. To my amazement, even the 'ridiculous fighting tournament' storyline was strung in quite well; it didn't seem out of place at all. And even more amazing, the addition of the P3 characters; also seamlessly added in. Nothing felt tacked on or forced; it was all good stuff.
This was a smooth move and something I totally did not expect. Here I was, enjoying a Persona-experience (story/character-wise) without the RPG. This wasn't just a Persona cash rip off, it was the real deal. Before I knew it, I was playing not necessarily for the fighting, but for the campaign with its hilarious/meaningful dialogue, interesting story direction, and overall persona-charm.
What a pleasant surprise. If you're a Persona-fan of the Atlus faithful, you're not going to be disappointed with this addition to the Persona series. The caveat, of course, is that if you're not a Persona fan, you might not be as impressed with the campaign as I was. The game's story is clearly catered to veterans of the franchise, because there are a good deal of cameos and overall nostalgia factor.
All in all, I'm glad I played it. With the recent price drop, the game was definitely worth it.