Just took the Step II CS today.
First Aid for Step II CS is excellent preparation. The practice cases and minicases are EXTREMELY similar to what you will see. I read this book cover to cover over the two days before the exam and felt very well-prepared during the test. (and I hadn't put on a stethoscope, palpated an abdomen or thought about heart, lung, GI, renal differentials in over 1.5 years).
One thing to decide before your exam day is whether you prefer to handwrite or type your note. The USMLE website has the program that you use if you decide to type so you can try it out before hand. I would definitely recommend trying it out. Pick the style of note you prefer and stick with it through the test day.
Overall, you don't need to sweat this test (2 days prep is ample), but I wouldn't go into in blind either b/c it's not like examining real patients -- there are quirks particular to the test that you need to understand before taking it. First Aid tells you everything you'll need.
Good luck and enjoy the light meal they serve you during the day, after all it's costing you $975. That's the priciest meal we'll ever have.
