CPU rendering already gets speedup from E-Cycles, but most of it comes from using the presets and new options. CUDA and Optix have the now pretty huge out-of-the box speedup on top, that’s why I focus on it, but I have several CPU and OpenCL users. YOu also have the better denoising, the streamlined UI, the tutorials, reduced noise, new samplers, etc.
You can get an example of CPU usage of E-Cycles by @bernardo here.
If you are on Windows, the pre-processing time is also greatly reduced in many scenarios with latest E-Cycles 2.82 builds.