These Mayne window boxes are beautiful and smart.  There is no need to paint, and any dirt can be wiped away easily.  They are durable and roomy.  I have 6 plants of various types and sizes in each of mine; these planters are ample in size.  I live in FL, but these window boxes give a Northeastern feel.  They have a built in irrigation system, which helps to keep the soil moist yet not overwatered.  I could not be happier and would highly recommend. They are also preassembled, so simply require being mounted to your window sill.

Pros: Beautiful and cottage like feel
Cons: None, easy installation.