Also, an interesting quote on it from reddit.
woah! the difference between the two images is perfect. The 2012 protrays a fresh confident and proud rover, eager and excited for it mission.
what amazing possibilities it must dream of: vast uncharted land. a pioneer and seeker of knowledge and truth.
however the second image, the most recent image, portrays the years of wander. the alien landscape, the numbing hours of ceaselessly plodding along, the isolation. the rover is worn down, eroded by his task. his burden. he feels doubt and perhaps the reality of condemnation has finally set in. "WHY! why have they built me? doomed me to wander this desolate rock?"