Earlier this week, Raj Singh graded the OGC's services against REST and then graded the REST architectural style itself:
The fundamental problem with REST and GIS in my opinion, is that REST optimizes for data access, and OGC services are optimized for data processing. I consider GIS a type of OLAP system, and we as an industry will continue to resist REST because it would be counter-productive to expose data via atomic resources that all had their own URL (and metadata!?!) because everything we really want to do with the data would get harder.
In comments, Stu Charlton points out that REST is in fact optimized for data processing. Myself, I think it's simply in a different style, one that looks more goal oriented or agent oriented; I've linked to a past post by Charlton on hypermedia agents that has many good comments of its own.
Is it true to that the GIS industry resists REST? Some companies and consortia do, others don't. It seems like there's a press release about a new Geospatial REST API every other day. We've just seen a "REST API standard" document released by the 800 lb gorilla itself. A lot of this is just marketing, but there is also a growing, honest interest in resources instead of endpoints and HTTP as an application protocol.
I'm not sure grading OGC services benefits anybody, but if you absolutely have to grade your services against a REST maturity model it's probably best to use a standard model.