I gave a lot of thought to getting the new 50L to have a fast, 'normal' lens for a trip to Japan. I went with the 35L instead, partially because I'm shooting 1.3x and 1.6x crop cameras, and partly because the 35 and 85 were my favorite focal lengths back in the film days. It seemed like an awfully expensive addition to my bag, especially since I'm already shooting the 10-22, 17-40L, and 24-105L in that range. I brought a lot of gear to Japan, and surprisingly, the 35L was one of my most-used lenses. Great for low-light, nighttime stuff. The bokeh really surprised me...not as buttery as my 85L, but beautiful nonetheless. And did I mention I focuses about 5X faster than the 85L?
In the field, this lens went from a 'just in case' tool to a main everyday workhorse. I always have it tucked in my pocket now!