REST is a good set of design suggestions for designing web services, but, like anything else, don't get too caught up in adhering to the philosophy. Use the techniques that will work best for the problem you're trying to solve.
SOAP should be avoided at all costs. It has no redeeming qualities whatsoever and was probably responsible for the Teletubbies. In any case, REST applications tend to be designed more around a "give me this chunk of information" and "put this chunk of information there" concept, whereas SOAP is a bad attempt at doing RPC over XML over HTTP, which probably isn't what you want.