Sorry, I'm from EU. It is a type of investment similar to CD with gov. help...
Yes it is insured by state. 3.4% is interest rate, and I would be limited to ~5k per year. My other savings goes to 3fund portfolio.
Considering that my 3fund portfolio is in USD, I was thinking to add this as diversification (fixed interest) and currency risk (it is in EURO).
Overall for next 20 years I would gain more from funds, even taking currency risk into account, but 3.4% fixed in not too bad, however not even close to potential 7%+ from funds.