Manga Studio EX is the most advanced edition of the Manga Studio suite from SmithMicro. This suite is the most handy tool for those who love to author comics and/or mangas. First of all, you get a bunch of great (and domain-specific) tools like G, Maru and Kabura pens... you will see them nowhere else. All these great tools are carefully arranged in an improved environment, featuring redesigned smart panels, divided in tabs and hidden (although still accessible through the collapse button) to save space for the canvas.
The support for layers is also great: it's prepared for very complex, layered sketches. It's just as good as any serious drawing/photo retouching suite.
But this program is not just about drawing and putting text balloons: you can choose from several predefined page layouts (divisions) and apply them with just one click. Another interesting feature is the story editor: just like a text-only editing mode, allowing separation of concerns on multi-disciplinary teams (like an artist and an editor).
Of course, a program with such overwhelming set of features comes at a noticeable price; but if you are seriously committed to the design of comics, maybe you can judge better if it is worth it.