It looks awesome!
The one thing I would do is when you color, you need to make the colors more dynamic. By dynamic meaning, not all the same hue, each time you pick a darker color, move the slider over a bit. By doing that, you make the colors more vibrant. Even if you're not going for a vibrant feel, selecting the right colors can add to the "faint" or "pale" feel.
Like, if you were shading something green, each time you dropped down a shade you'd move the hue over to the right (I think The side where it's bluer and greeneer)
If you were shading light blue, almost teal, like what you have, you'd move the slider over towards purpleish blue.