I did Casaval Ridge over Memorial Day WE, 2009. I had a blast and recommend it. It really was not difficult. There was a section or two of exposed, steepish snow and some scrambly bits on rock. My partner had almost no prior mountaineering experience and he was comfortable climbing it ropeless.
That said, we did meet a party from North Carolina who felt the 'Catwalk' was too exposed and traversed climber's left to finish via the West Face. A rope and a few pieces of gear, and of course the skills to use it all, could be helpful in a few spots to increase the saftey. I met a party on the way down pitching out a section (I was downclimbing).
Also, there always seems to be a question about where to camp, whether to carry over or downclimb, etc. The tatic we chose worked really well. Here is a link to some words and images from my ascent: http://themountain-life.blogspot.com/2011/02/absolute-beginners-guide-to-mt-shasta.html