[This is an excerpt from a longer description I wrote for friends. The eclipse took place (for us) at 10:21 local time on 2017-08-21.]
We viewed the eclipse from high ground in central Oregon near Walton Lake in the Ochoco National Forest. We chose a viewing location with clear views to the WNW, and set up tripods, camera equipment, and a small refracting telescope with a solar filter. As the eclipse began, forest service and fire crews showed up at our location to watch. We gave them some of our excess eclipse glasses. Late in the partial phase, our shadows became really strange, with corners and pinpricks in our shadows turning into thin crescents. The light became strange—dark and direct, like the world was under tinted glass—and it started to get cold.
The eclipse glasses were magical; the full disk of the Sun could be viewed comfortably and inspected, and the cut from the Moon was dramatic. Through our small telescope, sunspots were visible. Another crew at our site had a larger reflecting telescope set up, also with a Solar filter. They had an astounding view of the sunspots.
But the transition from even a tiny sliver of visible Sun to totality is astonishingly stark! At totality, the sky became dark enough that we could see a few stars and planets. The corona of the Sun could be viewed directly without the glasses, and it was visible by eye out to a full Solar Diameter away from the eclipse limb. There was lighter sky at the horizon, and it was pink like a sunset in every direction! That, along with the enormity of the corona, was the most surprising thing about the eclipse for me. It was dark everywhere like late dusk, with late sunset on every horizon. It got cold enough that those of us fortunate enough to have brought sweaters to the viewing point put them on. The corona of the Sun was almost triangular in shape, with a dark black hole where the Moon lay.
Towards the end of totality (that is, about 2 minutes after the beginning of totality), we could see the light racing towards us from the WNW: The more distant hills lit up first. At the very last moment of totality a tiny pinprick of sunlight appeared on the limb of the sun making, with the ring-like corona a "diamond ring". Instantly it was too light to look at directly and we put our glasses back on.