QGIS is genuinely remarkable. The fact that something this capable is free and open source fundamentally changes who gets to do spatial analysis and mapping.
The QT5 to QT6 transition was no small feat either. I remember when that upgrade seemed like it would take years. The fact that it actually shipped and works well says a lot about the volunteer maintainers who show up.
What strikes me is how FOSS tools like this quietly enable whole categories of work that proprietary alternatives would lock behind paywalls. Not just for individuals, but for communities, NGOs, small government agencies. The "I can't believe this is free" reaction is the right one.