Voyager is a beautiful example of reliable code and engineering. 30 years and 10 billion miles out, and still functioning.
As an engineering approach to generating power, thermopiles are considered differently today than in the 1970's due to environmental and health risks associated with plutonium and the probability of a launch failure.
Shortly before Cassini was launched there were some people on my college campus protesting the mission on grounds of risk of radioactive debris spreading if the launch failed. Motivated by my distaste for fearmongering, I did some reading and found that nearly all the scholarly research and engineering studies suggested the risk was infinitesimal, and in a worst case scenario the spread of dangerous concentrations of radiation would be highly localized.
Aside: Bill Nye (himself a trained engineer) also uses his position as Executive Director of The Planetary Society to advocate for the use of nuclear power generators in deep space missions.