The mission has been a very popular one with the American people and the world at large. Spirit landed in the Gusev Crater on January 3, 2004; in the following week, NASA's website received over 1.7 billion hits, breaking the records set by previous NASA missions. Although the mission life of the rovers was originally set at about 3 months, NASA has kept extending the mission, even to today. Since April, Spirit, which has reached the 500-sol mark on Mars, has been trying to climb the Columbia hills.
And for those of us who can't get enough of Mars, NASA's Mars Reconnaissance Orbiter will be launching on August 5, 2005...
For more information:
NASA's Mars Exploration Rover Mission Webpage
Wikipedia: Mars Exploration Rover
And if you want to read about the sibling rivalry going on between the two rovers...
Spirit Rover LiveJournal
Opportunity Rover LiveJournal