The job does look pretty decent. I am very OCD so i would have done it different. For what had to be done I could tell that it probably works well just doesnt look that well.

i would have.
-move tubing and drain to left side
-insulate steam hose or move unit to left side plenum
-cleanup control wiring
-installed EIM module above anything with water
-installed a 4" media cabinet under furnace
-straighten flue pipe
-hard piped gas line. some code mandates flex because of earthquakes. i dont know if Arizona does