In our back yard in Durham it was noticeably less hot. Almost pleasant. For a few fleeting moments, anyway.
We used a cereal box viewer. It took some tweaking to make it satisfactory. I tried simply poking a hole in the foil with a pen, a pin, an awl, a screw. Each of those gave me a pinhole with square corners, because of the way the foil folded. Finally I put duct tape on both sides of the foil, then sandwiched it between two boards and drilled a hole in it. That gave me a beautifully round hole.
At one point some clouds passed in front of the sun, and the camera obscura view of that was maybe cooler than the eclipse itself.