I thought the random generation was pretty good especially since you said it was the first time doing it. I think one thing as far as the gameplay goes, I'd suggest maybe making the phoenix a bit more challenging. I know that if you kill it then it will multiply, so I naturally stopped shooting it and just started avoiding it. Maybe as you collect more souls you could increase the speed of the phoenix that way it might force the player to want/need to shoot it in order to get away from it.
Great work though! Congrats on your submission.