Great PR brings joy, pride and meaningful admiration from peers and the general public. And putting NASA's project New Horizons in perspective shows that the 700 million budget has been a great PR investment for the so far. Compared with other PR investments, for example a main sponsorship of the Olympics, a Soccer World Cup, Formula 1 or similar sport events, it's a fair budget and the ROI is extremely high.
In this perspective NASA is a great PR investment for the USA. Vlad Savov at The Verge has compared the NASA investment made by the US Government with other corporate invenstments in order to put things in perspective. For example: Apple could fund 15 New Horizons project with the profit they made in the last three months only. Read The Verge article here.