I liked this one, both advanced and challenge version.
I'm only having problem with the clarity of the new cross bullet type. I think its animation should be slightly reworked. Now it's impossible to predict its backward movement direction or how much time it will be spinning in one place before going back. Where there is a bunch of single crosses that came from different directions it creates complete chaos and all you can do is either guess or memorize their further direction. I'd really love to see some changes to make cross boomerangs more similar to homing bullets which changes their animation depending on their behavior.