I love the two face portrait thing here you have some nice work here I would suggest some borders or frames to accent it all a little better, Portrait art is always difficult to do I like the artist's use of darkness and shadows here yet again, They were able to capture all the facial details and expressions perfectly, I love artwork that combines two different things, like the two faces here. It's so different from other types of art. It's very creative and difficult to achieve.
~~THINGS TO IMPROVE ON~~
I would suggest some borders or frames to accent it all a little better