I have a relative who moved from Kent to the Shetlands for a quiet life in his late 50's. It seemed like a great idea at the time.
Given the opportunity, I'd like to live in Shetland, though I don't think that SWMBO would embrace the idea (we'll almost certainly stay in rural Shropshire). What I like about Shetland is the scenery; the wildlife and the fact that it hasn't been 'ruined' (thus far) by over-development. It is far less 'touristy' than the Western Isles - (relatively) little provision is made for tourists.
National Geographic rated it as 3rd best island to visit . . . . . . .
http://www.saxavord.com/about-shetland.php
Lonely Planet also rate Shetland very highly . . . . . . .
http://www.guardian.co.uk/commentisfree/2010/nov/02/shetlands-scotland-islands-discovered-uk
Your relative possibly found it to be quite a culture shock - I'd feel much the same way, if I had to move to London or somewhere suburban. Of course, the weather in Shetland can be very harsh at times and like anywhere, it can be hard to feel at home, if no relations live close by. It can be very cold and I believe that the highest windspeed in the UK was recorded in Shetland.
For families, Shetland can be an attractive place to settle - there are jobs to be found; the schools are excellent (the Secondary school has been rated as the best in Scotland) and it is a 'secure' place to live, with particularly low crime levels. The elderly are very well looked after and generally held in higher regard than elsewhere.
He's now is his 70's and would love to move back to the South East to be near his family and support networks but is priced out of the market.
I can well believe that ! Property in Shetland is much cheaper than on the Mainland. Many people who move to Shetland can buy a property outright and still have a fair stash of cash 'leftover'.
My Grandmother's croft house and land (a modest 25 acres), sold approx. 15 years ago for a massive £8,000. Mind you, since it wasn't on the Mainland, a bit of island-hopping was required to get there. As is required by Crofting Law (I believe), it was offered to family members first, but none of us wanted it
at the time . . . . . . . I really wish that I had bought it, though !

Mind you, my Aunt's place may come up for grabs . . .
Did your relation live in Lerwick ?
Pedantic hat on

- it is correct to refer use either 'Shetland' or if you want to make it clear that it is an archipelago, 'The Shetland Isles'; but never 'The Shetlands'