If someone offers you 10% interest, it is practically a given that the whole thing is not very trustworthy. I assume therefore that people investing in Iceland only did so with superfluous money that won't be missed too much.
It was about 6%. Not market leading but competitive. The main reason why I opened the account was that it was one of the few ISA providers accepting transfers in.
They have more of my money than I would be happy losing but I consider myself to be more fortunate than most. I believe my position, and salary, to be secure for the next two years and icesave only has about one-quarter of my savings.
Of course, if you lose the principal, it's not likely to pay off now, but still impressive.