Nightsky, I don't know what field I'd claim to work in, but I'm part of a 6-person state policy & planning unit which includes one certifiable GIS genius. I focus on water resources and, in my ~ 7 months in this job, I haven't used our pretty amazing GIS set-up even once. Years ago I intended to do a lot of GIS, but it never caught my fancy and the limited skill I once had evaporated between then and now. That's one problem with GIS; it is a situation of use it or lose it.
Although GIS apparently isn't for me, I would highly recommend it to anyone as an accessory skill to enhance whatever it is they know and do. Geography departments have spent 20 years churning out narrow GIS specialists and I worry about the long-term future of students who don't combine it with something else. But, if you figure out a way to combine it with what you already know or are interested in knowing and it can be golden.