From the NEJM blog:
The classic manifestations are headache, jaw claudication, PMR, and visual symptoms. However, 40% of patients present with less typical manifestations, such as breast or ovarian masses, peripheral neuropathy, SIADH, or mesenteric ischemia.
Let's not forget aortic aneurysm and/or dissection, which can show up years after remission of GCA.
Regarding treatment, steroid sparing immunosupression seems popular in practice. However, the blog author pointed out that such agents have not been validated by high level evidence.
What the post left out about treatment is that low dose aspirin reduces vascular events and is now a recommended adjunct, along side steroids, in the treatment of GCA.
The primary NEJM article is here.