Pretty slick. It’s fascinating how you managed to make it difficult with such a seemingly game-breaking mechanic. At first, you might think it will be very easy since there is no limit to how long you can stay in bullet time, but the introduction of enemy shields makes the real challenge more about proper positioning and being able to reach the enemy’s weak point using the character’s unique moveset. That’s a very good workaround, and it works well.
As a result, the game is now very challenging. Some may like it, some may not, but in my opinion it’s hard by necessity, and with practice anyone could surely beat it.