I have some spare time and I finished it! I'm pretty happy about it. Next time I'll try to do it more speedy. For the hair I used a custom brush.
The time it taken is pretty much the same as if I'd drown it in PS. Waiting layer merge, "borderless brush" and modify selection, that should speed the process even more. Overall I prefer BI over PS even for this kind of stuff. Another thing I have to do next time is to take the figure separated from the background so I can easily paint on in at the end of the drawing.
edit: I forget to mention that this image is very big, and with PS I certainly would had some lag.
If you didn't notice i'm very happy of BI