its primed, it has wood grained look and will last forever. It needs painting and caulking after install, and since its a playhouse, I would NOT allow the ends of the masonite to touch the ground. This is where it will rot out. Have the house on 4x4 posts acting as skids and stop the masonite at the top of the 4x4's.
I have it on my work shed and its been there for over 12 years, I just paint it every year, which is not necessary, I just like to keep things for ever.