I thought he was great! I don't like that Part One didn't reveal much of his background with Ethan, but maybe Part 2 will when it comes in 2025. I loved Esai's performance and his cool lines and especially his fight with Cruise at the end.
I also agree with @Beetlestar , he was a very dangerous villain and perfect opponent for Ethan. He knows who Ethan is, and how he can hurt him. When a villain knows the hero that well, they can inflict all sorts of pain on them.
I also loved Lane, Walker and the Entity!