I love homes from this era! The quality of the materials, at least among the homes still standing, is often excellent. This is anecdotal, but I find that they also tend to have a lot of natural light and stay cooler in the summer.
Double hung sash windows are especially popular in this era because they are designed to maximize airflow. You’d open the bottom sash’s on the cool side of the house to let cooler air in and open the top sash’s on the other side to let hot air out. This also creates an airflow across the home.
Heck, even the mirror in the bathroom opens and closes perfectly and it’s 110 yrs old.
The downsides are there was zero insulation in the walls when we bought it and the leaded glass windows are single pane. I’ve mostly fixed the insulation problem but the windows will always be pretty to look at but inefficient.
To be fair, "nothing" is like, the best thing you'll find when you look at the insulation in old houses.