I once built a 4x4 stand similar to that, but on the ground. First time I tried shooting at a deer with a bow, the limbs of the bow smacked the inside of the blind when I shot (arrow missed by a mile, too). If I were to do it again, I'd make it 4x6 or larger, and align it so I could shoot out the long way - not the 4' way.
As already noted, carpet all over the interior would be helpful to muffle any noise.