Swing is swing, it's as good as it's always been (eye of the beholder). As I understand it, it hasn't completely rotted on the shelf, they've made updates to the rendering to better leverage modern hardware, but it's not a modern toolkit by any means. But it is maintained, it still works.
JavaFX is good (I really like FX), and maintained, and portable. They just came out with 25 I think. But it's a completely different model than Swing.
Sure, but the same might be said of the subset of Java that existed twenty years ago; this is different from what people mean when they say "Java's good now".
JavaFX is better than swing, having done both (swing in a past life). CSS support is the big deal, plus modern rendering pipelines. Add that to the nice FP goodies and for-real cross-plaf packaging, (plus LLMs to get you through the crufty bits), it's IMO a serious contender for desktop UI.
I wrote a swing app a long time ago (20+ years ago) that was used in operating theaters to register organs for transplantation. Swing has saved many lives since. Swing has been good enough for a long time.
As a point of reference, JetBrains platform is on top of swing, and I'd guess that's a significant contributor to why they're able to deliver consistently across Linux, macOS, and Windows. Unlike Eclipse SWT which ships native code for all the platforms it targets
My understanding is that JetBrains puts a heroic amount of effort into making their Swing components not look terrible, and that they can do this because they're a well-resourced engineering-centric company whose main product is a GUI app whose users spend all day in it and often pay for it out of pocket. That Swing might be underrated for this use case (if you also need to ship cross-platform) is an intriguing possibility, but different from whether it's a good choice for the marginal GUI app.
It's as great as it ever was. I like it as its very stable and has a good model of interaction but if you want a modern embeddable map or embeddable chart stick with web interfaces. If you do go with swing definitely check out flatlaf to make it look modern.
