A lot of the good stuff (Curiosity, etc.) gets a ton of PR, but that doesn't mean there aren't day-to-day problems that are massive impediments for NASA. The mere fact that successive administrations get to come along and yank on NASA's long-term planning like a dog on a choke chain is really damaging to NASA's ability to actually break beyond LEO.

Until someone is able to marshal enough political power to force a change to this constant interference (and protect them long enough to accomplish their mission), NASA is going to continue to have trouble. Great engineers can still do incredible things even with bureaucratic and political interference, it's just so much more difficult than it needs to be.