Very bland and unchallenging. Terrible mechanic where your shot powers down as you shoot.
Update: I've removed the stuff about the leaderboards being broken since the devs say it's been patched.
Also, I discovered that you are awarded points for stars remaining at the end of the game, so if you're frugal, you can get a big end of game bonus.
The problem is that powerup drops throughout the stages seem to be random, so somebody who has a lucky run can keep their shot power up and get a few lucky bomb drops and not really have to spend anything in the shop.
edit: Aaaaah! There is a hidden mechanic. Once you get 100 stars, each star you pick up gives you an extra life, so don't spend anything in the shop, and then you can just tank your way through the final boss and get a huge bonus.
I spent a load of money on bombs before the final stage on my most recent run and I didn't have to!
I was wondering "hang on, where did all those extra lives come from?!"
Edit: yup that's the way to score big. Spend nothing in the shop, tank your way through the final boss https://www.youtube.com/watch?v=DugRvCvOSOg
edit:To be fair to the devs, they say they're gonna change the mechanics based on feedback, so hopefully the game becomes a lot more fun to play.

Very bland and unchallenging. Terrible mechanic where your shot powers down as you shoot. Update: I've removed the stuff about the leaderboards being broken since the devs say it's been patched. Also, I discovered that you are awarded points for stars remaining at the end of the game, so if you're frugal, you can get a big end of game bonus. The problem is that powerup drops throughout the stages seem to be random, so somebody who has a lucky run can keep their shot power up and get a few lucky bomb drops and not really have to spend anything in the shop. edit: Aaaaah! There is a hidden mechanic. Once you get 100 stars, each star you pick up gives you an extra life, so don't spend anything in the shop, and then you can just tank your way through the final boss and get a huge bonus. I spent a load of money on bombs before the final stage on my most recent run and I didn't have to! I was wondering "hang on, where did all those extra lives come from?!" Edit: yup that's the way to score big. Spend nothing in the shop, tank your way through the final boss https://www.youtube.com/watch?v=DugRvCvOSOg edit:To be fair to the devs, they say they're gonna change the mechanics based on feedback, so hopefully the game becomes a lot more fun to play.