With reference to the UK:
Structured deposits should not be confused with structured products.
Structured deposits are often, quite simple deposit accounts. You place your money into what is essentially a deposit account, and are therefore guaranteed not to lose your capital as with any other deposit account. The attraction is that you could earn more than you would in a normal deposit account, often around double, due to indirect exposure to the markets. Another benefit is that structured deposits can form part of your annual cash ISA allowance, so the returns can be tax free.
These products are popular with those who have savings which they are happy to deposit away for between 3 and 6 years, and are looking for better rates of return than standard cash ISAs or savings accounts.
The main drawback is that you may not receive anything other than your original deposit. That poses a minimal risk if your savings are earning less than 1% currently.
See my article at financialandrew.blogspot.co.uk/2013/03/fed-up-with-low-returns-from-cash-isas.html for a more rounded overview of the structured deposits.