Well, the PhD is NOT a professional degree or at least it should not be.
In statistics, my field, the PhD is ALMOST like a professional degree since there are many, many exams and courses. Most statistics is actually taught at the GRADUATE level, and NOT THE UNDERGRAD level. I have both masters and bachelors, and believe me, you learn twice to three times as much in the masters as in the undergrad. The PhD courses then delve into the theory of probability and mathematical rigor, which the masters courses do not. This is yet another big jump. The masters courses are more about basic theory, linear models (which is tied to expeirmental design), and applications to clinical trials, survival times, missing data, experimental designs. Many of the pharmaceutical companies absolutely want the PhD, and will not take a masters, although that is not necessarily true with the financial companies. However, a professional degree per say prepares to take the licensing exam to be a certain title, or profession, just like the name and IS NOT RESEARCH BASED AT ALL. In fact the rotations in the fourth year almost serve as one's INTERNSHIPS in pharmacy school in the diferent possible settings. I still think the PhD would be better if there was something similar as to the fourth year of pharmacy school but in conducting research. However, this might be different in PhD programs in pharmacy. I only know about statistics.
PhD is all about research. It is supposed to open your doors to academic or industry research. Academic research does involve teaching as a component.
Sometimes, a PhD is not enough, as is the title of the famous book related to the science fields, "A PhD is not enough". Many factors contribute to your success or lack of after you receive a PhD. Some of it depends upon reputation of your advisor, quality or your resaerch, and MOST IMPORTANTLY, either YOU or YOUR ADVISORS CONNECTIONS INTO INDUSTRY. If you are applying for an academic position, sometimes a postdoc is required sometimes it is not.
The postdoc is a chance to better prepare one for academic research usually. It is like buying more years in graduate school to publish papers. Again the effectiveness of the postdoc depends upon the same factors as the effectiveness of the PhD. I have a friend in my statistics program who has been doing a postdoc for 5 years in chemistry after a PhD from Peking University, the best school in China, published several papers in physical chemistry, and could never land an academic position. He is currently pursuing a masters in statistics.
Drawbacks of PhD: Unlike professional school, one's fate is often unknown.
You could graduate with no job, an OK job, or a very good job depending upon several factors, including hotness of the field, your connections, and who you are working with on research.
Advantages of PhD: Allows for more independent thinking and the potential to really delve into your field with a true passion. The PhD in pharmacy, by the way IS NOTHING AT ALL LIKE THE PHARMD! Nothing in the PharmD can even prepare you, since you never conduct much research. It seems like at UF, the long projects that some people on this forum complained about, are opportunities to see whether you will want to pursue research after the PharmD. At UF, which is a research based school, the professors seem stricter and give more projects because they are hoping that some PHarmD students WILL actually go for their PhD later. hence you see that the magna or summa cum laude students HAVE A MANDATORY RESEARCH PROJECT. Hence these projects seem to not have much to do with the NAPLEX, but instead are trying to give the students a glimmer into what it is like to delve deeper into their field.
A PharmD scratches the surface on the sciences, while a PhD delves deeply into them.
I repeat, only pursue a PhD in pharmacy if you have a true passion for it and YOU NO THAT YOU WANT A PHARMACEUTICAL INDUSTRY JOB OR A FACULTY JOB. If you are in the PharmD and can't wait to get out and make money in retail, then do not do it. But if you truly love what you are learning in your curriculum, then by all means go ahead. The PhD will help use the basics (in other countries, PharmD is still the B.S. in pharmacy which is just a college degree!) and go far, far beyond. Prepharm is usually taught in high school somehwere else and is incorporated into the college entrance exam, at least in China.