Okay, finally got a chance to play through the new gauntlet mode - a blast! Here are my thoughts:
I love your aesthetic, and I feel like you added a lot to the enemies, bosses, and stage BGs.
The rechargable weapon mechanic is great - not sure if that was in when I first played. I also like that there is a focus/spread fire and autofire (this already existed fo sure, but want to praise it)!
Some good difficulty increases, some bosses are appropriately danmaku now :) Also new and interesting patterns (and enemy types, those ghosts that shoot triples are great!) in the levels!
Two things I'd like to see:
1. one more level of harder difficulty: I made it through gauntlet in one try - two bosses almost killed me, and I was definitely sweating some part, but I'd like that 'aspirational' difficulty level that makes me feel like I have to level up to make it through.
2. level/boss select - a common feature and great for practicing (especially if you put in another diff. level)
Great work! I would def recommend this, especially to new shmupper!