I was thinking of buying this just to try the new features (since I still have my original PS discs). From what I can tell, the new things that are added are achievements, cloud saves, some kind of character editor, and some fixes to old bugs/glitches.
While looking on the forums earlier, someone did find a old bug inside the game involving the Save Crystal and the North Crater: Stuck in the Northern Crater on FF7 for PC
Here is a article passage involving the new features:
The Final Fantasy VII PC website teases several new features. The game
will get unlockable achievements, "cloud" saves (hopefully the pun is
intended) as well as something called Character Booster.
Character Booster will allow players to automatically max out their
in-game health, experience and Gil (Final Fantasy cash, to the
uninitiated) in order to cruise more easily through the game's
legendary story. It's not clear if that will involve micropayments or
Cloud saves will let players save their games to Square Enix servers,
so it can be continued on more than one home PC or laptop. This is not
dissimilar to Valve's Steam Cloud on the Steam digital distribution
platform, and comparable features on Xbox Live and PlayStation Plus.
Where to download(since I see people asking in other threads): Square-Enix Store - Final Fantasy 7 PC