I.e., the question you’ve all been asking yourselves.
If you haven’t been… get with it, man.
So why do we care about landing on Mars?
One obvious reason is that it’s a bitch of an event, as indicated by the Seven Minutes of Terror a craft must go through to reach the surface. The US has succeeded in 6 out of 7 Mars landings, which is 6 more than any other country. Curiosity will also be the first rover to land on difficult terrain, which goes to show the great leaps and bounds NASA has achieved since it started sending rovers to Mars.
But most importantly, thanks to Curiosity’s size (roughly ginormous, compared to previous rovers; in fact, ginormous enough to carry multiple chem labs), we will be able to hunt around for the ingredients of life. Overall, Curiosity will be examining the history of the planet, with an eye out for any carbon-y goodness that may indicate there was once life on Mars.