Edit: Since this initial review, the game has now become free, so I've upped the score from three and a half to four stars, since free is a pretty big plus.
It's a shame that this game is only available if you pre-ordered Final Fantasy XV from Gamestop. That said, if it does become available for purchase later on, the content involved doesn't really justify anything more than say, $10.
The graphic are beautiful sprite graphics that are quite detailed, and the sound is nice and retro as well. Combat is really smooth and lets you rack up combos easily, and there's just enough different moves to keep things fresh without making you go 'wait what's that combo do again?'
Unfortunately, if you go into this expecting a real prologue to FFXV, you'll be disappointed, there's not really much in the way of a story. A few characters are introduced but don't do much other than give a few more special moves, and there's no upgrade system or other RPG elements, so by the time you get to endgame, you might get a bit bored. All achievements are fairly simple, and the whole game can be 100%'d in about 4 hours, so that's nice. But, there's no real difficulty in the story mode (You most likely will need to grind out the death achievement), and the extra battles don't offer too much variety, so once you finish the game I doubt you'll pick it up again.