Ajax and REST
Good introduction on some of the benefits of REST, primarily caching and lower memory usage on the server side.
Brian Repko: Ain't gettin' no rest with REST.
Benjamin Carlyle: Common REST Questions
See also: Benjamin's REST Tutorial
I think this discussion illustrates the biggest problem with REST: it's hard to understand. Conceptually, REST is pretty easy. Use the HTTP verbs. Post some XML. But when you start doing more complicated things than creating a new record, there's a lot of disagreement about the "right way" to do it.
I mean, listen to this: "That is not to say that REST can't do transactions. Just POST to a transaction factory resource, perform several POSTS to the transaction that was created, then DELETE (roll-back) or POST a commit marker to the transaction."
I get what Benjamin's saying here, but it's not easy...
Maybe the real problem is that SOAP was too easy. It hid the complexity of what was really going on, but the abstraction was too leaky. Network calls are not like method calls. REST tries to rectify that, but it puts more of the burden on the developer to do it right.