There are alternatives to this product out there (e.g. commits.io) as well as manual approaches, but the interface that CodeNail provides is really handy. On a "business" level, I really think that the FAQs are super helpful and the pricing breakdown is really clean/obvious to the reader.
All in all, I can see myself purchasing one of these posters in the near future.
Simple, intuitive, and easy to use
Somewhat pricey but not unreasonable (in-line with competitors)