The Leica M-E has a better sensor type than most cameras that have been around for a similar time to it. This camera has a CCD sensor type, whereas most MILC digital cameras that were released more than two years ago have a MOS sensor type. CCD sensors produce high quality, low-noise images but consume a lot more power than CMOS sensors. CCD is the most common image sensor type used in digital cameras.
This digital camera's sensor type (CCD) is actually the best sensor type across all digital cameras of a similar type and age to the M-E.
The worst sensor type amongst similar types of digital camera is MOS.