Very, very stylish -- love the pixel art. Power ups are fun, but don't seem to make a big difference in gameplay. Would be nice if there was some strategy in terms of positioning/aiming. E.g. player can rush the net, making their shots move faster, but is then vulnerable to a lob powerup, But all in all quite beautiful and nicely done.
Also, I really need to check out Pico8, looks very cool.