Creating or updating products with Magento SOAP v2 API - a very challenging adventure

In one of our current projects we have to set up a Magento shop for a customer. This project includes the development of an import / export interface to his ERP system. First, I had to make the decision which of the offered Magento Core API's I'll use: XML-RPC, SOAP or SOAP v2. I personally dislike XML-RPC webservices, so I had a closer look at the older SOAP API and the newer v2 one.