I think it probably gets a bad rep when compared to "modern" UI development frameworks, however this thing is still trucking along all these years later. I'm not sure I'll need to touch 3.1.5, but it's just really cool to see it still being worked on.
I think the biggest thing the project needs though though is... documentation. Or maybe it has it, but needs some serious SEO work to make it better accessible? So much of my time was spent trying to figure out what specific feature flags meant, whether they were still valid, and so on. I've done Cocoa development for years, so I'm used to outdated/old documentation, but with wxWidgets it just felt... harder to find the right stuff. Maybe because the userbase is smaller in comparison?