Even though people are saying that it's common sense, many of them won't be able to identify very basic components of document credibility, argument reasoning etc.
It does seem like common sense but the subject will help you gain critical and analytical skills for when working with your other qualifications as well as real life.
Main keywords that we were taught already (BEERVAN): Bias, Expertise/Experience, Reputation, Vested interest, Ability to see, Neutrality
By learning the actual definitions of these words, mixing up 'bias', 'vested interest' and 'neutrality' will not happen as often as I see people do!
It's the first time I've done such a subject, really. Did do a small tryout on a past paper last week - miserably failed (U) - despite the questions being 'common sense', answering them was just impossible - overwhelmed my mind and I gave up >(
But I'll get it right, eventually - Critical Thinking is not that hard - just use the right language (that's where I lost most of marks in the questions that I did attempt).