I was never a fan of Materia Keeper, simply because the fight was always the same. He'd cast Trine repeatedly, murder my entire party. Cloud would be the only one alive, and he'd get a limit break instantly. He'd bust out Cross Slash, paralysing Materia Keeper for one turn, which Cloud would use to heal himself. Rinse and repeat.
No matter how many times I've played the game, it always go down this way. It's not a hard fight and I'd never die, it was just kind of boring.