Many of the SOAP based web services out there have parameters of specific object types - so not just simple String/int inputs. The ADF Web service data control makes it quite simple to interact with them. And this applies also in the case of ADF Mobile.
Since there were several thread on OTN asking about this - I thought I'll do a quick demo to refresh people memory about how you pass these "complex" parameters to your Web service methods. By the way - this video is also relevant if you are not doing mobile development, you'll basically use the exact same process for building "regular web" ADF applications that access these types of Web services.
One more thing you might want to do after you create the page is look at the binding tab to see the method call in there, and notice the parameters for it in the structure property. Go and look at their NDValue property to get the complete picture.