The face is currently fine. The colours are also good, in my opinion. I personally think the pose is too stiff, though. Wouldn't the viewer see a different angle for both legs? When both knees are bent the same way, and the feet face the same direction, it looks very artificial. The arm holding the sword is the same. Perhaps try big, flowing lines to plan your image, instead of lots of small anatomical segments.

Keep up the good work!

Is there a reason the samurai is smiling? It sort of offsets the rest of the image, which has a very dramatic atmosphere. Something in general reads as off to me about his face, but I'm not sure why.