Ed, I was actually just about to ask whether any of the people who use it as a Service Desk platform heavily adhere to the ITIL framework. I was going to ask as I cannot imagine being able to use WF to do so. As a PM, I have been leading a project for our firm to move to ServiceNow for IT Service Management for the past 2 years (we moved Triage, Incident, Major Incident, Problem, Knowledge, Request, CMDB, Change, Request, and Asset Management over last year, year 2 is about enhancements and additional processes). While all of the basic abilities are certainly present in WF (taking in incidents and requests and assigning them), ITIL is so much more than just ticket management. I would love to hear how some people have accomplished alignment if they have.
On the DevOps side, obviously WF can be used from a software defect management standpoint, but so much of DevOps relies on theory of automation and that isn't something I see WF doing. You could argue that the workflows you can create somewhat match that, but true DevOps would say you wouldn't have a server request workflow, a developer would log into a store front (like vRealize or Puppet) and build the server themselves, no approvals/workflows required (assuming it is a server that falls within certain tolerances). WF can do a lot to bring teams together and since DevOps does rely on bringing resources from various traditional teams (development and network operations) together, it can certainly be something to help facilitate the practices of DevOps. But, like most things, you can't say, "we have WF, now we can be a DevOps shop."