Got 2:30 of totality in MO near St. Louis.
As has been said - All partial eclipses are roughly the same. Perhaps after about 75% occlusion you could feel the heat of the sun as considerably less intense. It was very hot where we were, so being able to stand in the sun and have it not feel warm was noticeable. It was fun to watch the moon slide across, even a little ominous, but it's not changing much on Earth.
After maybe 90-95% occlusion, you can convince yourself that it is getting dimmer. However, it is nothing remarkable. Shadows are still very strong and the sky looks maybe a shade darker blue.
100% was completely different. Nothing like anything I have ever experienced, even after I had bought into the hype and was 'ready' for it. In about 5 seconds all the light just dies as the moon pops over the last piece of the sun. Surreal. Looks like someone took a hole punch to the sky.
The sun's corona is also remarkable. Those gas plumes are gigantic. Impossible to see at any other time.
The darkness is comparable to maybe 30-1hr after sunset. You can see bright stars and planets. In future eclipses with wider bands I assume it will be even darker. The main source of light seemed to be scattering from 30+ miles away where the sun was not blocked.
Temperature dropped maybe 5-8deg F total. Much appreciated on a warm and muggy day. Definitely worth braving a plane flight and some traffic to see.
Seek totality if you get the chance, one of those weird experiences we are lucky to have on Earth. History is littered with accounts people awed by it -- you will understand why when you're there.