Is that the t-stat wire going through the return grille?
Only two things I would have done differently.
1. Standing S-Slips for anything 18"+ in width (SMACNA standard).
2. The square throat/radius heel elbow coming through the wall is less than ideal, especially on the supply side. That is the 2nd worst elbow flow wise (after square throat square heel without vanes). A square elbow with vanes in it would have been much better IMO seeing as how a 1x radius throat would have pushed the duct too far off the wall.
Otherwise it looks pretty good to me.