"until we can clearly state how we do it, we cannot claim that we know how to engineer it and that we can do it successfully in the next project" - quality inconstancy.
"the need for rapid feedback and the evolving nature of the program-under-test" - features of intangibility.
"there are usually no deadlines" - extended timeline, results in each period are different
These all are distinguishing characteristics of services, not products.
Therefore, I'm more inclined to the "service" view of software testing.
Dmitry Plavinsky, QA Manager