no, they are actually quite harmless to humans, they are predators to little insects though, so leave them on the bushes. They are definately a beneficial insect. They are scary looking and they will follow you with their heads....eery.
They do bite when threatened, and the bite can be large and quite painful. I've never wanted to even try to pick one up. Many years ago, I got bitten while weeding in the garden. The mantis was exactly the color of a dry dill stalk. I never saw it coming!