I grew up on the Lizard, and moved back but to SE Cornwall in 1990, with DH who had just taken an internal company move from overseas, and I have been here since.
Cornwall has changed rapidly since this thread was really live, but on the back of a fabulous Easter, I imagine there are other people who'd like to know what it's really like.
The first point to make is that you need to have a proper, confirmed job to make the move work. And despite everything you read in the papers about the shortage of staff in the NHS and teaching, it doesn't exist here. A teaching or NHS job will pay much the same as anywhere else in the country, but because of location pull, there will be people applying from all over, attracted by the quality of life. Teaching jobs, just for example, are much more competitive, and I understand from friends and acquaintances, that medicine and nursing jobs are too. You get paid the going national rate in a county where wages are very, very low -- which makes you among the best-paid people in most villages. Or there is agricultural labour: wages may improve when farmers can't get Rumanian pickers, but lifting spuds or picking daffs and plucking seaweed in the rain isn't intellectually stimulating. Or it's seasonal, and usually low-skilled. Think scooping icecreams, waiting in a tea room or cleaning for women.
That said, property prices are very high astronomic compared to salaries as there are so many second/holiday/letting homes which is fine if you own one, but it prices out many families with ordinary breadwinners.
However, if you are a successful freelance something (as I was) and prepared to get up at 3.00am twice weekly to be in London for a breakfast or early morning meeting so you still command metropolitan pay rates, or have a business you can move here and work online, then it's very fine.
It's better in winter than summer, because it's not so frantic, but the lifestyle is great, the coast and country are beautiful; and the food offering is improving all the time.
And I think it's much less insular and parochial than it used to be. When we went to Cornwall as a family in the early 60s, no Cornish person was friendly to my mum who was 27, knew no one, and was a 10 hour drive from her family, with two small DC. She hated it, but was sentenced there for 12 years. She would tell you she loathed the place.