Sennheiser ME66 is not a good choice if you want to mount it on the camera ENG style. It is a long shot-gun meant to be mounted on a boom pole.
Let's say you mount it on a camera and try to get some sound bites during an event, the mic picks up all the noise behind the person talking... as it is a highly directional mic, i.e. it picks up everything in the narrow angle, short and far...
If you want a mount-on mic, get ME64 or equivalent short shot-gun, i.e. the pickup pattern is wider and shorter (good for picking up two person talking) and it does not pick up too much of the noise behind the people talking. The sound in the direction is attenuated after roughly a few metres...
I have tried both extensively.