Using today's low interest rate as an example, if the interest rate is hiked, the old bonds lose value esp. the long-term bonds. Hence, the low-interest bonds today (again particularly the long-term bonds) are risky. For me and me only, I buy long-term bonds when interest rate is 8% (higher or lower is defined by you) or higher.
Using China as an example, when the USD appreciates (as in today) and the loan is in USD, China would win as the payback in USD today is worth more in buying power than before (or comparatively to Chinese currency). The country should appreciate its currency but in reality all want to depreciate it to boost export.