The new Cambridge Thinking Skills assessment, which most colleges now set for most subjects to all candidates, is very similar to Critical Thinking questions.
Furthermore, i have applied to many different companies for summer jobs, and a lot of them set tests like these as a preliminary 'hurdle' to immediately reduce the number of applicants. The Critical Thinking course was definitely worth it is this respect.
I personally only did it because my headmaster started it this year for oxbridge and law applicants, so i only really went along because i got a free lunch from him twice a week!
it's not difficult at all - a lot of common sense and logic. I revised for a total of ten minutes for the mock (no exaggerations) and got an A.