According to my save file it took above 80 hours to complete this game. Now I don' t know if that's true because I am playing this on PCSX2, and when I'm in dungeons I use turbo mode to save time grinding, which most likely resulted in the game clock speeding up. A friend of mine beat this game in 40 hours, so I'm going to assume that this game took me 60 hours to beat since I spent a LONG time grinding.
I got the True Ending, ended up with some pretty high level personas, Level 83 Kohryu, 63 Black Frost, 70 Loki.
Kohryu wasn't utilized fully since the final form of the boss absorbs lightning magic. I avoided use of all lighting magic and used the main character for buffs and the occasional Mind Charged Aragidyne (heavy fire) to the boss. With Mind Charge, Increased Damage, and the bosses defense lowered, Aragidyne did about 700 damage. But having all those three buffs and debuffs on at once is very difficult to keep up.
I was just one spell away from defeating Shadow Mitsuo, and I forgot to use Me Patra. One thing I don't like about this game is the fact that if Yu/main character dies, it's over. It may make sense according to some story point or something to do with the fact that Yu is the Fool Arcana. So I guess it's just one of those chosen one things.