I used my trailer for a winter then had custom built double pane windows made for it. So I had the unique opportunity to see the change with the same rig.
Big difference!
Less condensation, much quieter inside, more private (I have tinted glass), and a bit warmer. The frames are non-thermally broke aluminum, so they do still sweat. But the glass doesn't get as much moisture on it and, what does condense clears off shortly after I open the shades.
I prefer winter camping (usually with lows in the 30's to negative single digits). But even for summer camping, they really help.