my storyboards are suuuper rough. I usually just draw stick figures/lumps to get a general idea of each panel. I'll also write in the dialogue/text so in case I want to change it. I have most of the text written out in a document as well, but sometimes I don't realize that something is too wordy until I've written it in the panel.
When I first started my comic, I didn't use storyboards because I thought "why bother?". I felt that if I were going to be drawing anyway, I might as well put that energy into actually creating my comic. After a while, though, I realized that planning it all out page by page made it much easier and quicker, among other things.
I leave the storyboard as a layer underneath the finished product in Manga Studio. It's like a little secret buried beneath all the other layers ^.^
here's my most recent storyboard for Reus, though in all honesty the final product may very well be quite different.