I like it, looks great.
I have to say though that you'll need to add filters over the vents. If you don't they'll soon cake up with paint. I have made one similar and got slack on changing/adding filters and mine quickly got all caked up.
Something as simple as an easy 2 stage filter. First use a thick (3/4"??) furnace filter directly in front of the fan and then a second filter in front of that. The second one can be another furnace filter type of thing...but thinner, more like cloth. They sell them both at hardware stores.