Assessing 21st century learning and teaching?

The Program for International Student Assessmet (PISA) Math scores from 2012 were released in December 2013, ranking students from Asian countries at the top of the list, with Finland being the sole non-Asian country included in the list of top performers in science.

The top performers in math: China, Singapore, Hong Kong, Taiwan, South Korea
The top performers in reading: China, Hong Kong, Singapore, Japan, South Korea
The top performers in science: China, Hong Kong, Singapore, Japan, and Finland 
(Source PISA 2012)

According to the PISA website, since the year 2000, every three years, fifteen-year-old students from randomly selected schools worldwide take tests in reading, mathematics and science, with a focus on one subject in each year of assessment. The 2-hour tests are a mixture of open-ended and multiple-choice questions that are organised in groups based on a passage setting out a real-life situation. 

They and their school principals also answer questionnaires to provide information about the students' backgrounds, schools and learning experiences and about the broader school system and learning environment.

PISA claims that it is "unique because it develops tests which are not directly linked to the school curriculum. The tests are designed to assess to what extent students at the end of compulsory education, can apply their knowledge to real-life situations and be equipped for full participation in society" (PISA website).
Sample questions can be found here.
What do you think about PISA's claim? Are these questions and tests an effective way to measure learning that is important to real-life situations and for full participation in society? How do PISA scores and ranking matter in 21st century learning and teaching?  What are alternative methods of finding out how students are acquiring 21st century competencies?