Over the last two years my organisation has been working with multiple partners helping them create partner integrations and showing them how to use the variety of SOAP APIs available for Sales Cloud integrators. Based on this work Ive been working with development with the aim to simplify some of the API calls which require "multiple" calls to achieve a single objective.. For example to create a Customer Account you often need to create the Location first , and then the contacts and then the customer account.. In SalesCloud R9 you will have a new subset of APIs which will simplify this.
So you all have a head-start in learning the API I've worked with our documentation people and we've just released a new whitepaper/doc onto Oracle Support explaining the new API in lovely glorious detail. It also includes some sample code of each of the operations you might use and some hints and tips!
Enjoy and feel free to post feedback
You can download the documentation from Oracle Support, the document is called "Using Simplified SOAP WebServices" , its docId is 1938666.1 and this is a direct link to the document