I use a pen tablet yes
drawing with a mouse is a chore for me.
BUT, there are some people who do some miracles (well..it's matte painting, not digital painting).
Here's an example of what Christian Lorenz Scheurer (a swiss matte painter) can do:
(matte painting is a procedé where you only use textures and photographs to "build" an image...it involves little actual painting and you have to be a master of your tools for that
though i'm far from being that crafty with photoshop. Though give it a look, type Christian Lorenz Scheurer in google and see
)