I played and finished it on the PS2 twice. The only enemy I couldn't get past was Sephiroth, but he was optional so I didn't worry about it. Then I got KH2 and finished that game too. There were a couple of things I never finished in that game as well. I never got into any of the mobile games.
Then I got the big box set called "The Story So Far" a few years ago for the PS4 and ended up replaying KH2. I didn't even realize I was playing the Final Mix version until I was about 1/4 of the way in. I also finally got to play a few of the games that I had skipped like Birth By Sleep and Dream Drop Distance.
One of these days I'll have to go back and play the FM version of KH1. I have KH3 available to me but I haven't started it yet.