With my Yashica TLR it's all positive, some smiles or curious looks, people poking each other, pointing and smiling...comments like wow that's a beautiful camera.
With a 50mm prime on my F100, not so much...as others have said, with a larger lens people do notice and try to get out of the way when I don't want them to. They duck or turn away, change direction to walk behind me etc. A big lens pointed in someone's general direction will make them uneasy, that's been my experience.
When I'm out on the street now I usually shoot with my Olympus stylus epic. It fits in the palm of my hand and I can shoot it one-handed when necessary. It's a great camera and I am rarely noticed with it, even shooting in close quarters, people don't seem to care.