Nice room! My first inclination would be to paint the wall surrounding the brick in a color to help the brick blend in better. The white doesn't seem very complementary to me. A medium or dark gray maybe? Darker would help make the tv disappear. A beautifully stained wood mantel would look nice with your brick and against a dark gray wall.
Not sure what your plan is for the bookshelves, but I would minimize the number of "things" on either side of the fireplace and remove the deep lower cabinet unless you absolutely need it. You could hang the guitar on the wall to the left of the fireplace, and a grouping of larger art to the right. Alternatively, you could use the area to the right as a small sitting area with a chair, table, floor lamp, tall plant. I would remove the floor to ceiling wood panels that are boxing the fireplace in as well.
Q