So my day job involves designing and building a Web service for use by customers. We started out by building a service designed to meet the needs of a particular client, but I immediately started working on something generic right after. I began by looking at the SOAP option, but I wound up building the service using HTTP POST and an XML document as the response (in what I guess would be called a REST approach). I abandoned SOAP because I was in a hurry and the toolkits looked hard to use and I was intimidated by interop issues. Anybody can formulate a regular HTTP request and parse an XML document.
The upcoming question is whether to go back and build a SOAP interface as an alternative to the REST interface. Here’s a post from James Governor pointing out that developers just don’t care for SOAP, which certainly mirrors my own experience.
Update: Karl Martino forwards a quote from an interview with Flickr CEO Stewart Butterfield:
Koman: Do you see Flickr and its open API as representing a next generation of web services? What things can developers learn from what has happened with Flickr?
Butterfield: On the strictly practical side, I think we had one person inquire about using the SOAP version of the API. I don’t know if any apps were actually built. There is at least one application built on XML-RPC. But all the others–I don’t even know how many there are–are built on the REST API. It’s just so easy to develop that way; I think it’s foolish to do anything else.
I definitely think REST wins the popularity contest. Most of the clamoring for SOAP seems to come from people with an interest in buzzword compatability.