It's watercolor mainly. Looks like the weeping angel (don't blink) has some inking on it to create the darker lines but that could be a heavy use of the watercolor paints as well.
You can find brushes as mentioned above searching (with quotes) "photoshop watercolor brushes". You can see the layering of the brush strokes which could be achieved by making sure the pressure or opacity of the brush was set to 30% or less. Bear in mind, this is not a drag to paint type of brush but one that someone created, usually with real paint, then scanned into the computer and made a brush out of.
When you paint this way, you set your opacity and click the mouse once placing the pixels on the workspace. You can also reverse the effect to get a real feel to it by using other brush strokes and the eraser tool set to very low so that you get the feeling of different lengths of bristles for the brush.
Here is a quick one I did, not the same style but you get the point:
And here is a link to a nice collection of brushes.