I really like the Isle of Man. I ran from one end of the island to the other last summer and it was looking beautiful. I'm surprised by the comments about it being expensive - maybe compared to Cornwall or the North of England it is, but not compared to quite a lot of the south east. You can certainly buy a nice 2-bed semi for £250k which would be completely impossible here. It's a lovely place to go for a holiday, particularly if you like old trains and transport.
It's largely frost-free, probably more going on culturally than Cornwall, to be perfectly honest, unless things have changed since I lived down there in the early 90s. The east side of the island is in the rain-shadow of Snaefell, so there is fair amount of variation in climate across the island. If you don't like the weather where you are, you can usually drive a short distance and get something different. It's all windy though.
The vast bulk of the population is local and is not associated with financial services shenanigans and although it does feel a bit like going back in time, and it's pretty conservative, crime is low and I don't think there's much ill-feeling to non-locals
My possibly false impression is that it attracts people who've made enough money that they want to hide from the taxman, but not enough that they can afford to go to Monaco or somewhere nicer, so it's great if your idea of retirement is playing golf with your fellow scrap-metal merchants and car dealership owners. I guess if you're sufficiently rich to need to live there, the extra cost of travelling anywhere else, and the expensive gas & electricity don't really factor.
The presence of motorbikes travelling extremely fast on the island's roads for a good part of the year would be enough to put me off wanting to live there, tbh. No speed limits on many roads, and a lot of villages and houses have crash barriers on every corner.