Yup. I haven't built anything of significance in it (yet) but it's proved really easy to learn, and (again, in my limited experience) rock-solid stable and fast enough:

A trivial example:

  #lang racket
  (require net/url
           racket/gui/base
           racket/sandbox)

  (define (menu-file-exit-click item control)
    (exit 0))

  (define frame
    (new frame% [label "Demo"] [height 480] [width 640]))

  (define menu
    (new menu-bar% [parent frame]))

  (define menu-file
    (new menu% [parent menu] [label "&File"]))

  (define menu-file-exit
    (new menu-item% [parent menu-file] [label "E&xit"] [callback menu-file-exit-click]))

  (send frame show #t)

... is all you need to create a basic GUI app with a File -> Exit menu option. And that really is all there is - no resource compilation, no code-behind, no separate languages for expressing the UI and the actions connected to it.