My first thought was similar to Moira's in that this is quite flat tonally.
We always talk about a full range of tones in an image, but this is one where that doesn't have to apply (though we could make it so) because there is
a limited range of tones.
What is does benefit from is more contrast as Moira's mods show, just to give it more visual 'bite' or eye appeal.
And yes, toning is another option on top of that, (subtle) warm tones for being soothing, and you can choose one that goes with your decor.
A word of warning though, creating different toned mono image can be very addictive!
Composition is always more subjective with abstract images because they are just that, abstract.
A good play with light and shadow, too.
However, there's less going on on the left hand side, and a squre crop would look very good keeping attention on the framework and shadows.