Certainly the default L&F is not native looking, nor are any of the popular community L&Fs. Though one can simply set the L&F to the native look and feel with essentially one line of code. The little care I'm referring to is around polish to get beyond the lowest-common-denominator. Regardless, system L&F with Swing is still worlds better than any Electron app, which is now a common technique to build cross platform apps.