Since it all matches the floor, it really does fit in with the decor. I would not paint it. Its nice just the way it is. White will cheapen it.

I agree, especially that you will end up with something very cheap looking In reality, no fireplaces are "today'' and even throughout history few matched the "decor". They are all grand stand-alone statements, and it would be nice to find a way to have yours work for you. Painting it is not going to improve it or make it less of a huge old fashioned thing.

If you had something more beautiful in the arch, something that accented your home and your other decor choices, would that interest you? People would need to see more of your decor in the surrounding rooms.

What is the white rectangle you have on the non-mirrored side? I can't tell looking on my device.

IMO the mantel and the mirror are the big isssues and painting stone is not as easy as you might think The side with no mantel I would look for ahuge piece of ar to cover that arched part. and the same on the other side to rplace the mirror . remove that really clunckly mantel replace with a nice simple thick wood one like a shelf. I often paint FPs but IMO that one would not look better but what I suggested would tone down all the stone.

I’d embrace it — I think it looks great on both sides, and from what I can see of your decor, fits nicely.

I like the mirror and mantel and would just add some pretty decor on the mantel.

If the tile was of low-quality and truly ugly, painting would make sense. But your tile is good-looking and desirable, imo.