Looks like blue to me too. Blue will often have black "ink spots" bleed through. The genotype for blue is two "extended black" genes (the black gene) and *one* dilution gene. If you have two dilution genes, you get an even paler gray called "silver." Dilution is only partially dominant, so black sometimes shows through.
Now, I don't know how this works, but one of my blues has quite a lot of brown on her, which made me wonder whether she might not have some other colors in her. But her genotype appears nevertheless to be regular old blue, because the breeding between her and my blue drake resulted in a black (which means the baby didn't get a dilution gene at all, which will be the case for 25% of blue x blue offspring) and a silver (which means the baby got a dilution gene from each parent, resulting in two dilution genes--also happens for 25% of blue x blue offspring). I didn't get any blues out of the mating, but I only set 5 eggs, only three hatched out, and one of those was from a different mating. I have another six eggs in the incubator from that same mating, so we'll see how her genotype plays out in a larger batch in about four weeks.
So, anyway, the main point is that you apparently can have what appears to be brown in a blue duck, and it's still genotypically blue. Also, due to the variable action of the dilution gene and its only partial dominance, blues just tend to vary A LOT.
So I would say you've got a blue there. But I have been known to be wrong, probably more often than not.