This piece made me stand back a little and almost made me a little uneasy - mainly because it wasn't quite what I expected. You have produced something far more dark and contrasting than you have done in a while, which reminds me more of your earlier work. However you have combined a range of quite diverse patterns and styles which show your increasing confidence and abilities. The tightness and intricacy of the patterns in the centre, moving out into more open, free shapes is really effective. The movement of shapes and composition cleverly leads the eye from the open space at the bottom, almost as if following a pathway into the heart of the piece.
I find the thick diagonal lines at the top of the picture slightly distracting and yet they also help to lead the eye and keep the balance, somehow fighting with and yet bringing harmony to the rest of the piece.
It is a very edgy drawing, shouting at you to embrace it, dark and forboding yet strangely hypnotic.

Clean or not, I really like this picture as is, and I think the dirtiness that I think you're talking about adds a lot to the piece. It gives it some depth, by creating a greyish tone, instead of just being black and white. It's not something we normally see in your pieces, but here it seems to work really well! Since the lines are so dark and close together, it makes certain parts stand out more (like the loopy designs), but it also really accentuates other parts (like the maze-like pattern near the centre), making it much more impressive! I really like it!