I just sat my USMLE Step 2 CK today and I thought I should share my experience about some things that I observed:
I took the exam after my Step 1. You do not have to take them in that order per se, but it really helps if you do as many concepts and exam questions have basic science in them (a lot less than step 1, but still significant enough). I used Master the boards as my source as well as USMLE World question bank, which I review below. Studying for the exam took about 3 and half months. It should take less than preparation time than Step 1 as the material is relatively easier, However, do not be fooled. The exam is not necessarily easier than Step 1!
I used Master the Boards as the review book for the exam. It is a really nice book, and definitely helped a lot. What you should know is that it is not a comprehensive book. Ideally, you should combine resources as no one book is the one for Step 2 (there is no book like First Aid for Step 1). It all depends on how strong your foundation in clinical sciences is. I personally did not go through the Kaplan books, but some say that they are beneficial but more time consuming.
USMLE World Qbank: Absolutely essential and a great companion to Master the Boards. It offers exam style questions that are similar to what you will eventually see in the real exam. Make sure you go over the whole thing before your exam. There are around 2200 questions, average time to go through them is about a month.
NBME Shelf exams: They are a great way to know where you stand in terms of studying. What you should know, however, is that for Step 2, they are not as accurate as Step 1. I know friends who had a good deal of fluctuations between their NBME and their real score. It's a really nice way to know if you're really bad/good though
You have to keep in mind that the exam is longer than Step 1. There are 8 blocks instead of 7. You have 45 minutes as break time, so the total exam time is about 9 hours. The exam does not just test your knowledge, but also your endurance. Even though it varies between people, I found it to be very convenient to do two blocks at a time and take about 15 minute break in between. You can also take a one minute break and not leave the room between individual blocks jut to refresh your mind. If you finish a block in less than an hour (which, I'll have to say, won't be very likely), then the extra time will be added to your break time. Each block contains 40-44 questions (variable, unlike Step 1). If you get a block with less than 44 questions, then you know that that block won't be so easy!
The Step 2 surprised me in the sense that I thought it was really difficult. Exam questions are much longer than Step 1, so you naturally need more time per question. You cannot depend on reading the last part of the question only like Step 1(although it helps to do so before reading the whole case as it helps you know what you are looking for) as the answers can change according to individual cases. The problem with Step 2 is that clinical guidelines are not as clear as scientific principles that are in Step 1, so you are likely to see questions where more than one answer is correct and could be indicated. Bottom line is, questions are not as clear, so my advice is to go with your first hunch when you answer (read the question, have an answer in mind, and look for the answer that is closest to what you thought).
Time management is a very important thing in Step 2. I was faced with situations where I could barely finish the questions in time. If you find yourself stuck on a question without a clear idea, answer the first thing that comes to mind, flag the question, and come back to it later if you have time.
Drug Ads/Abstract questions: This is a unique type of questions only present in Step 2. There will be sets of questions (2-3 questions) that are based on Research abstracts of clinical trials or Drug Ads (which they will obviously provide) and you will answer accordingly. Make sure to review your statistics knowledge and practice how to criticize clinical trials as you will be asked to make a recommendation to a patient scenario.
Enjoy! you finished a really tedious exam! you are one step closer to your dreams!
Sorry for the long post. If you have any questions, please let me know.