Downsides: volatility, still new-ish, non-trivial to secure for regular folk, zero recourse if hacked/stolen

Upsides: Money/valuestore that is infinitely divisible, scriptable (m-of-n, "smart contracts"), reliably and inexpensively transmissible world-wide, offers financial services to third world and unbanked, potentially less volatile than some fiat currencies, potentially resistant (not immune) to manipulation by governments, potentially usable as backbone for "internet of value" applications (side chains, colored coins).