In my opinion, I didn't think the exam was that bad, especially when compared to the MPJE. It took me roughly 4 hours and that was with quadruple-checking my answers to calculation questions. To study, I used the RxPrep book/online questions and felt like questions on the NAPLEX were pretty similar to what you'd see from the RxPrep online questions, perhaps even a little easier. The estimate of my NAPLEX content breakdown is as follows -
25-35 questions on Calculations - Some say use SDN120, but RxPrep was perfectly sufficient for the difficulty of questions I saw.
20-25 on Infectious Disease
15-20 on HIV, Compounding, Appropriate counseling of medication side effects/administration/etc.
5-10 on Immunizations, Heart Failure, Diabetes, Oncology, Asthma/COPD, Biostatistics, Hepatitis/Cirrhosis, Anticoagulation, Female Hormone-replacement, Choosing an appropriate reference
Those are the content areas/topics I specifically remember. Looking back, I really wish I'd studied Infectious Disease/HIV more in depth because it seemed like I got slammed with those questions. I don't know, however, if everyone generally gets the same amount of questions per content area or if it is random in that respect.
Biggest piece of advice? Don't be nervous. Statistics are on your side as the nation-wide first-time pass rate is over 80%, so you're way more likely to pass than fail. Just remember that fact if you begin to stress out.
Best of luck!