Gitify is all about making your life easier. It just does a job. Sitting on your menu bar it informs you for any GitHub notifications without being annoying and of course without adverts.
Gitify will notify you every time you receive a notification by playing a sound (not an annoying one - promise), by showing a native OSX notification or by just turning its tray icon to green. It is not there to interupt your workflow or distract you at all. It's your buddy.