Lorna Mitchell has posted a review she's done of the Packt Publishing book "RESTful PHP Web Services" (by Samisa Abeysinghe).

Overall it was well-written (with only as many spelling mistakes as any other PHP book) and clearly organised. [...] Very few services that claim to be RESTful actually are, which makes writing anything along these lines very tricky, however I did feel the author could have been clearer about why having a single URL and a parameter for which action should be performed, doesn't fit well. We do get a sense of excitement about services as ways to "glue together" bits of data on the net, and the possibilities of exposing and consuming information in this way.

She talks about the quality of the technical content (including the "very thorough" non-framework examples and Zend Framework example) and some of the extra baggage she felt it could do without - specifically the overhead that adding the Zend Framework could add.