It just happens that I teach Knifty Knitter at Michael's, along with a few other classes. I was just looking at the craft boards, and saw your question.
Using it is really easy. I find that people always have trouble binding off. You have to use a crochet hook, I recommend a size I or J if you are using bulky weight yarns. I had a lady in my class yesterday who was so worried about that part, but she left happy.
See if your Michael's has a class. If not, you can always ask the Event Coordinator if they can offer one...I'm sure there are others who would like a class too. We just threw it on the calendar, and were surprised at the interest.
My 11 YO DD has a Knifty Knitter. It is very easy to do. Although, my mom has taught her how to knit the with needles, and she sometimes prefers that to the Knifty Knitter. It just depends on her mood.