I played this on stream for Feedback Quest 7. The VOD has been posted to youtube; game starts at 1hr 40 min in
I wish there was a health power-up the way you can also get shield power-ups, as there were times where I got obliterated and needed just one more health to have survived. Also, it's easy to miss unlocks. Maybe add a "stage select" or similar after a mission is complete the first time so that you can go back in and play the 2nd part, where you get ship unlocks, instead of having to redo the whole mission.
The ship with rotating shields was a solid option, as was the indestructible ship. The final ship that unlocks, the iron one, might be better if unlocked early and the tiny ship be the last one, since that ship is the hardest one to do anything with (it does provide a huge difficulty spike!)
Good fun overall!!!