Some early impressions:
It's basically exactly what I expected: the mobile version wrought large for the PC. The menu interface is slightly different, not scaled as large as in the mobile version.
But it's otherwise the same awesome redone character models and the same low-res background art with just a little bit of filtering done to make it not quite as messy (but still pretty messy). Supports resolutions up to 2556x1440 and makes full use of that in the newly rendered parts. Not just the character models but also the menu icons and the TT cards are all redrawn.
It feels a hell of a lot snappier and quicker to load than the original. Remember: turn on "Skip Battle Camera" in the options and it eliminates the pan over the battlefield at the start of all but boss battles. Also make sure you turn the Battle Speed slider to max. Do both, and you should have no complaints about speed even without using the 3x option.
I'm sure a lot of people are going to whine about the background art, but realistically this port is, I feel, better than I would have expected. It's certainly a nicer PC port than what FFVII and VIII got.