What a wonderful experience! A nice rewarding secret room, really neat little concept, and a fun dungeon!
I only really had two issues:
The dungeon design was a little odd at one or two points. It was weird to me that the first section had the key to both the first and second section, if I recall, and I was very confused for a while as to how to get the ice wand, since I was hunting for the second key in the second section.
And the dodging. The dodging felt very unintuitive and strange, and dodging away from my aim mostly felt bad. I think most games with dodge rolls (like Enter the Gungeon's great dodge roll) you roll in the direction you're moving and not the direction you're aiming, which works a lot better.