You could at least spray paint the brass black, with the right finish it could look very nice. Paint that dry wall at the bare minimum.

I would tear out the hearth and drywall and start over, tiling over the whole wall and hearth. And of course get rid of the brass.

Don't paint the drywall it looks great white. Cover the brick with some rough cut stone (see attached photo) but you do need to change the brass and cover the slate.

I feel your pain. We have that same brick and it feels a little lifeless to me. I really like the large format tiles that Carolyn Albert-Kincl Design posted.

I once had a very similar fireplace, and shown here was the simple fix (wall paint, roller, black spray paint for the brass screen) http://jansseninteriors.blogspot.com/2011/07/updating-fireplace-and-painting-brick.html Took about an hour and cost almost nothing.

If you spray paint the brass, make sure you use a paint made for high heat.

I work with this scenario often. Photo below shows a job I built for a client where the design required developing a sense of symmetry while also dealing with the uneven spaces on each side of the fireplace.

For your job I'd recommend
Phase 1-
1) Flat black over the brass

2) New granite (or slate to match floor) over the brick on all 4 sides of the firebox. 10-12" wide

3) New painted wood mantel mounted over new stonework

4) Miscellaneous woodwork to cover all brick below the height of the mantel top.

5) Narrow bookcase to the left of the mantel (depth of all woodwork needs to be considered here to meet fire codes)

Phase 2
1) Continue framing and drywall above and below existing drywall area as necessary
2) Lower TV
3) Add additional woodwork and molding details i.e. crown and picture frame molding

I think Interior International brought forth the pudding... And the proof.