Frankly and honestly, people in the UK were very open. Being that I grew up in Spain one tends to have a little more in common with people from Europe than say America (sports, exposure to various cultures and the like).
A lot of people were very curious about life in America and although they definitely had their perceptions of what it was like, clearing up some of the stereotypes was fun and quite revealing.
So to sum it up:
1: People in the UK are in much more knowledgeable about world affairs
2: The UK is EXTREMELY diverse, people from all colors creeds and nations speak with a British accent.
3: Very talkative, I was asked countless times from random people who heard me speak "What part of America are you from, oh I visited "X" place, it was grand".
4: Interesting fact, some people aren't over the Revolutionary war and are well versed in what battles turned the tide and how close we were to actually losing many battles.
5: A lot of petrol heads in the UK, like HARDCORE, know every F1 driver in history type petrol heads. I had a awesome conversation with a colleague on Francois Cevert. Whereas here in America most people have no clue of what F1 is.
6: Gas in EXPENSIVE!!! It's probably more than double of what we pay here in the U.S.
It was good experience. I had never been to the UK but I had a good time, I am looking forward to the next time I head over.