Is Blender substantially different/better than, say, Cinema 4D? Or are people more excited about it because it's free/open source?
Not sure I agree here! I work primarily in Substance Designer and Painter these days because I want more portability and basically everything has a substance plugin, or at worst I can export them for a regular PBR workflow, and I've played around with mari, and there's yet to be a situation where I thought I couldn't do the same thing with blender's node system.