Against all odds, the hero and heroine maintain their humanity under the most dehumanizing conditions. Against all odds, the hero goes "from rags to raga." Against all odds, the hero and heroine find one another again amongst the teeming millions -- ironically, by the blind leading the "blind."
If you believe that love is greater than money, that love between two individuals out of all the people in the world is incredible but true, that love is in short fate, then you will love "Slumdog Millionaire" as much as did my wife and I (an incredible match, by the way :)