IMO the paneling on the fireplace wall has to go - but I do think the FP can be left as brick. Paint the brass FP screen in heat safe black paint. Change window coverings to something lighter in both texture and color.

I'd also remove the paneling on the stair area. If possible, replace your railing with cable rail.

It looks like some of your paneling is the midcentury style that has no grooves in it. I think that can still work in many rooms if there isn't too much of it. I do think though that the paneling with the grooves needs to be replaced with sheetrock.

Replace your ceiling fan fixture if possible. If you *really* need a fan there, consider one of the Minka Aire fans that has much more modern styling and is less obtrusive.

Could you take and post another pic of whatever is in the 3rd photo? It's a little dark and blurry and I can't really see what it is ;-)

IMO this is a great room with tons of potential!