Hard, but for the wrong reasons.
This is a beautiful-looking game. However, the enemy bullets were impossible to see. Sure, you could keep track of them if you were looking directly at them, but when you have to focus on dodging the enemy ships, keeping track of exactly where your ship is, trying to plot pathways between bullets from different locations at different angles to try to get a powerup that's hidden amongst them, you run into bullets that you simply don't notice. They blend in with the background of stars, and when they're in front of a bright part of the background picture, they become nearly impossible to see.
This issue is easy to fix, though. The game seemed to have a lot of blues, whites, and reds. Making the bullets a bright purple or outstanding orange would have made them a lot easier to see, especially compared to the subtle offwhite they are now.
Secondly, why do you have to press a button to shoot when there's no reason to ever NOT shoot? You ought to either make the game have autofire or have mechanics that would require you to stop shooting. As it stands, I have to press a button the entire time I'm playing, which gets old quickly.