The greatest problem was that the comet was moving at around 11,000 miles per hour when Philae attempted to land. Things were looking great until the hooks that were supposed to deploy that would anchor the spacecraft to the comet, didn't work. Philae bounced around and Rosetta found it caught in a crevice and sent the picture of its condition back to the space agency.
Miraculously, Philae didn't get destroyed and it didn't give up and sent pictures of the area where it landed. It also analyzed the composition of the surface of the comet and sent the results back to Rosetta who forwarded it to the space agency. They couldn't believe Philae was still operating.
Unfortunately, because of its position in the ravine, Philae didn't receive sunlight and without solar power, its' batteries died and so did its mission. As for Rosetta, her fate was sealed when she ended up in the comet's path and was crushed.
Think about the above and let it sink in how brilliant the people are who work at the European Space Station. Everything they did to make this mission come together truly blows my mind.