Here is a great link to the hike, including a down-loadable map, elevation profile and trail description. Most trail guides and websites say the hike is "strenuous" and I think my friend Don would agree, but I felt it was pretty moderate, certainly no more difficult than climbing Lassen Peak. The elevation change is 2150 feet in 2.5 miles, which is about the same as Lassen, but here at Castle Crags you top out at just under 5,000 feet elevation as opposed to 10,500 on the peak.
No sucking O's on this hike, that's for sure.
Yet, in spite of the lower elevation you are up in the "snow" and "great view" country. Looking at the bare granite domes and spires, Mt. Shasta's white pyramid to the north, the Klamath Mountains and Trinity Alps to the west. South-east you can see Lassen Peak. There are lots of places to explore, and scrambling to do on the granite slopes.
After the hike, we stopped for a drink and food at the Dunsmuir Brewery, a great local hangout just three exits north. As we sat there in the sun, drinking beer and wine and listening to a local guy on guitar singing sixties tunes, I wished the day wouldn't end.