One of the great things about the Mars exploration program, brought about by the huge amount of high-quality images being sent by all the hardware we have there, is the sense of Mars as a real place. You know, not just as a dot on the sky, or this distant abstract "thing", but an actual place, as real as any place we have here on Earth, where things actually *happen*.
The first ground-level images we got from there, from the Viking crafts, were a start — but they were basically static. The idea was that of some unchanging expanse of rocks and dust, sort of like to Moon but with a bright sky. But the truth is very, very different.
In recent years/months, thanks to several missions (the rovers Spirit and Opportunity, the Mars Reconnaissance Orbiter, Mars Express, the Phoenix lander and others) we got (click on images for larger versions, follow links for more info):
I think the impact of those images, especially the animations, comes from our sense of celestial objects as places where changes take eons; they show us that this is not the case, that our neighbours can be dynamic, changing places. They give me a sense of the enormity of the universe, more than even the Hubble Deep Field did, because they make it seem more real. If all this is happening in our nearest neighbour... what else is happening everywhere else? What other wonders are we missing out there?
The universe is a great place, even if it's trying to kill us. I hope it won't be too long before more of us get to experience more of it.