I agree. Great job on completion....it's not about perfection! I'd say they need to start off a dark metallic color or a grey base. Pencil lead dust makes a good look, rub that in and put on a very thinned down coat of rusty brown and red. That'll give you that surface rust effect. For the all over dust, most easy would be a pigment powder from Mig/AK. Just brush it on all over with a semi-stiff brush and wipe it in realistic directions.
Even as it stands, it's definitely worthy of applause. Extremely fast and Accurate! 8)