Hi rawraw
Estonia is in the eurozone, which means that we are using euro as our currency (Estonia has been on euro since january 2011). While Bondora is operating currently in 4 (3) markets: Estonia (population of 1,3mio), Finland (5,5mio), Spain (46,6mio) and Slovakia (5,4mio - Slovakia is currently inactive due to less quality borrowers), all of those markets euro has been adopted so the only currency risk for foreign investors is EUR/USD when you are outside eurozone.
Bondora average return has been around 20% per year, this mainly because of Estonian people (currently 50-60% of the applications come from Estonia, Spain and Finland are almost equal with 20-30%) hasn't had too good access to money. So the interest rates are somewhat higher than you can expect from loans in US. For example average rate is 20-35%, depending on a credit group.
I myself believe that returns will fall in some near future (Bondora is negotiating with different institutional investors to take them on board). Also the whole credit model was redesinged in the beginning of this year giving more fairer options for both lenders and investors.
Should you be interested in Bondora? Yes, why not. But perhaps only with 5-10% of your portfolio. That would be my take on it.