Let me begin by saying I seriously struggled about getting this book. I LOVED (and loved to hate) FA Step 1.. FA + Goljan audio + UW for 4.5 weeks got me >230 after being a mediocre student for the first 2 years of medical school. I was 100% set on doing FA for Step 2 after I took step 1 but then all these reviews on Amazon and SDN scared me away so I started panicking and got Step Up to Medicine and got overwhelmed by it during my IM clerkship and then got MTB Step 2 and feel duped (too much obviously missing and I do not believe the reviews for it on Amazon anymore). I also bought Secrets to Step 2 and I really like that one but it's kind of hard to learn from initially but it's definitely a keeper.
Anyways, I ended up buying FA Step 2 CK and just started skimming it. I don't know why everyone keeps saying that it is lacking in information but then I remembered people used to say the same about FA Step 1. I'd constantly hear people saying that it NEEDS to be supplemented by RR or Pathoma or BRS or whatever. I ignored them and told myself if I could memorize every line in FA I will fill my little brain to maximum capacity for a single exam.
Now that I am looking at FA Step 2 CK, I feel like I can say the same... If I can memorize everything in this book + understand all answers of UW, I will feel confident about taking Step 2. Secrets for Step 2 will be my Goljan audio (mention interesting little high yield factoids). In summary, if you ignored the haters that told you FA Step 1 is not enough only to see for yourself that it was, then at the very least you owe it to yourself to give FA Step 2 CK a shot.