Love the cover art! It's obviously taken from Ninja Gaiden, but it's so expressive and it gives you an immediate feeling for what you're getting into.
The game controls well too. I noticed that enemies attack you from above, and you don't have a way to attack them back by pointing the ninja star upwards. That would be really helpful.
I also like that you gave me a little play space early on just to mess around and learn about the controls before getting hit with a bunch of enemies.