I'm playing right now and overall while I think the game is fine I'm having difficulty wrapping my head around the combat. Finding it a bit too hard atm. I did the weakest version of the Titan simulation fight at level 21 with all three divine shrines discovered and it took me 10-20 attempts.
It's tough to see enemy attack telegraphs and when there are more than one non-trivial enemies to fight it feels like a pandemonium.
How are you playing? You can complete remake as a hack and slash, but it's meant to be a fairly slow defensive back and forth while you build up atb. I'd assume rebirth is the same. Take your time concentrating on dodging attacks more than dealing damage, before unleashing chains of atb skills from the whole party at once.