Despite everyone drooling over how awesome this boss fight is I found it pure***** - the difficulty is OK, but everything that comes after the 2nd phase is just troll physics and enough visual effect to make someone go epyleptic. The dude jumps in the air, stays suspended for one second, then turns around 90 degrees midair and slams into the ground 100 meters away. He ignores physics so hard that it breaks the immersion completely for me, worse than Pontiff (at least he had wings) and even Nameless. His flaming cape, his crying-activated bullet hell, and the following lightnings serve little more purpose than to obfuscate the player's vision. I can't help that think From tried too hard to make the fight epic but didn't have the creativity to make it original, so they just put in the most amount of ridiculoud crap that they could.
Not to mention, that Gael is a noname, he had no business being the final boss of the series. He could have been a good optional or pre-final bossfight, keeping only his first and 2nd phases.