I had been using Bowtie up until a few days ago when I got SizzlingKeys. Bowtie worked fine for controlling iTunes with global keyboard shortcuts, but it ran as it’s own app, it froze up from time to time and it would sometimes get lost when disconnecting my second monitor.
SizzlingKeys runs as a plugin with a pref pane in System Preferences. Its functionality is solid and reliable and it can set shortcuts for essential iTunes functions and ratings. It also includes extras like assigning global keyboard shortcuts sleep, system lock and screen saver. If you’re looking for a very stable and functional iTunes controller, give SizzlingKeys a try.