The trick was that they treated "Graffiti" as a new alphabet that users had to learn. Thus, when the recognition engine failed, many users blamed themselves (i.e. their Graffiti fluency) rather than the product.

In contrast, when products that promised to recognize natural handwriting had a recognition failure, the users tended to blame the products.

It's a good lesson for product development--user satisfaction will depend in part on user expectations.