If you want to do away with the mansard roof, you're talking major construction. You can frame a 2-story with a gable roof and turn it into a colonial. Or just go with what you have. Cedar shingles would improve the look greatly. I'd also change that dark grey (?) color around the windows and dormers to something prettier.

I would concentrate on making the entry a focal point by constructing a pergola type look with colorful pots sitting on a new stamped concrete patio and walkway to the driveway. I would also light it with accent lights. The Landscape needs new sod lawn and possibly some arcs of Planters. Remember, color is light.