Just reading chapter 6 of Pro Paypal ecommerce and am interested in how people feel about using SOAP as opposed to Name Value Pairs (pg116). Although I've just done Sun's web service certification (or perhaps because of that ) I can appreciate the simplicity of the Name Value Pairs approach, and I think that is the approach I'd take to begin with although I'd be open minded and look at using SOAP if I started running into problems - but at the moment can't see any reason why I would.
My general answer to this question is that it depends on your programming style. If you prefer an object-oriented approach, the SOAP request and response types have a robust schema that, which complex at first glance, is actually pretty well-designed.
Agreed that the name-value pair approach is simpler though. We've seen a lot of uptake on it since we launched it in February. The code is much shorter as well.