I think it's cool. Agree with a suggestion of a single, striking item..wouldn't do a mirror btw-would go with smth more sculptural and personal. Mirror is a bit predictable..and it will take away from the arch I think. I wouldn't interfere with the arch-personal choice of course, but I happen to love arches. Especially the ones that are not crooked lol)) This is a well-executed arch. Agree with adding greenery(well I always do). Wouldn't paint it-unless you want to of course; what I would paint instead-the walls..but probably not a lighter color, but darker, mid-range color, so they become of the similar intensity of the brick. Brick will be less pronounced this way, but will be an integral part of this cozy, enveloping feel that a slightly darker tone provides. I understand the room is a bit dark; but it doesn't mean that light wall color will make it into a lighter room. It might, and it might not. I'd run with what I've got, and I must say-you've got a nice fireplace here..nice detailing on the walls..nice window frame..in short-to me, it's a great start. Wood floors would help of course, there's a bit of disconnect between materials like carpet and brick, imho..in general, whatever space you take. That's much more expensive though. But maybe worth considering, some time in the future. Again, unless you totally hate it(and then it's silly to make choices based on it)-work with it, not against it. Love that arch, the barnwood piece is fab!! BTW if you put a mirror not right across the window but on the wall perpendicular to it(the window wall)-that's how you'll get much more light into the room. I love, love Ingrid's painted fireplace, but it has a totally different character..as with people, you need to find a right..let's call it a key..to different rooms etc. It's not like there is what they call a master key-the one that will work anytime on anybody. Or anything, in that case.

My inclination would be to paint it black, not with chalk paint, but a high-gloss finish. Love something like this canvas for your room…bridge cables. $69.00 each…an industrial take on the high back dining chair. Rug has to go anyway, but it isn’t the right size/shape. You need something that is at least 2’ bigger than the table. Probably and 8 x 10. The wall decor, I am glad you are replacing it. I don’t think that mirror is the answer, though.

A rectangular interesting and colorful painting and just the candlesticks, with nothing else on the mantel, will look very nice, with perhaps a plant or foliage or flowers in a vase added. No word signs, that trend is over and it really never looked good. If you don't use the fireplace tools I would remove those too.

Love your bookends.... Going to suggest you lower your TV...looks so uncomfortably high but maybe it works for you. As for what to put on your table....how about the bookends with two or three colorful books between them. Put them on one side and a low green plant on the other side.