Martin Ramos gave some explanation of the difficulties on the recent failed attempt of K2.
The group he was with were told that it would be only a 4 hour climb from camp 3 to 4. The weather moved in though. Strong winds and snow hit the climbers.
Then there was the deep snow. At one stage he was almost sinking into it to his waist. They turned around at about 200m short of where they thought camp 4 was. Visibility was poor and they were not entirely sure where it was.
Here is his description of the difficulties at one stage,
“Gerfried, my colleague and leader of the expedition, began to dig a trench and move forward with piolet two meters every 15 minutes...It was desperate but he remained firm, behind Luis and me, and then Jorge and Martin, until we came to a stop very outstanding and a huge crack we closed the passage… Impossible to cross… We go down this dangerous place.” http://www.zamora.es/lang/martinramos/
Eventually they decided instead to head back down.