The USPTO open data portal is divided into four different sections. The first section leads to patent and trademark datasets. The second section demonstrates some of the amazing visualizations created using the patent and trademark datasets. In the third section, the USPTO is building a community around developers and other consumers of USPTO open data. I especially like the bulletin board-like user experience for developers to showcase their latest apps and visualizations.
The fourth section will be a library of APIs and is coming soon. If you click on the homepage icon, a PDF document [PDF, 666kb, 2 pages, April 2016] appears that displays the proposed layout of the API page: again, a good clean user experience design that will showcase the various APIs that USPTO has to offer. If the PatentsView API is any indication, the forthcoming USPTO APIs will provide great data with excellent documentation for both beginning and experienced developers.