I don't know GoodData from personal experience, but from looking at their website, I would say that some of the main differences are
- While QlikView is mostly maintained and serviced inhouse (installing of a Server, customization and creation of QlikView applications), GoodData seems to be a Software as a Service, where you outsource most of these tasks
- GoodData seems to use still "traditional" data warehouses and data marts, while QlikView uses in-memory data storage and calculation of measures during runtime
- as a consequence of first, your data will be hosted by GoodData, while you keep your data inhouse with QlikView (at least that's the standard model I know of).
Both seems to be pretty open regarding to connectivity, but I hadn't looked at the details. And both seems to provide "modern" web based access to the data / dashboards.
- GoodData seems to provide more like prebuilt apps, with prebuilt solutions, where QlikView offers some quick start apps more like a starting point, but both seem to promise building a business solution within days / weeks instead of months / years.