I've been running Hermes under Mavericks for two days now, and it's functioning flawlessly. This is a really neat little program.
What no one seems to have mentioned is that, unlike accessing Pandora via a browser, which, if you do not pay a monthly fee, will result in irritating advertisements, Hermes provides wall-to-wall music: no bothersome ads to break-up your mood. Together with all the other features that allow you to create new radio stations, or edit your existing stations, adjust volume, pause, play, skip songs, and either play/pause when your screen saver kicks in, I find that the avoidance of those irritating ads to be the great touch to make playing Pandora through Hermes a more satisfying experience than through a browser.