I grew up with, and went to school with kids who could draw like this. Abstract, "tagging" street art has always been a very popular form art. Simply because it requires no real structure or form. It's a type of expression. That's why it's popular and such a great type of art. It allows you a certain type of freedom and creativity that other forms of art really don't. Everything about it is great. From the details to the colors.
~~THINGS TO IMPROVE ON~~
No major improvment changes needed but would love to see some nifty borders on this.