I'm a surgeon in PP. As far as intellectually stimulating, it depends where your interests lay. I read up on things relevant to my practice. I go to conferences. I discuss cases with my colleagues. I don't do research. I like focusing on patient care. I don't like the politics in academics; there's still politics in PP, but it's different. I can work with students at times (individually, not as a group) due to connections I (and some other physicians here) have with the nearest med school; it's an option here rather than mandatory, although there are many places that don't even get the option.
I see all sorts of weird pathologies. I really do. My junior partner is constantly surprised at all the weird things he is seeing in practice that he never saw in training. If the management of something "strange" is something I am capable of doing (and that my hospital staff is equipped to handle), I do it. If anything, I can refer out things I am not comfortable with (for whatever reason) to the academic center, or patients who need care beyond what can be provided here.
There are certain pathologies that I DO think are better managed at an academic center. That being said, these things are often diagnosed/worked up/initially managed by those of us in PP before they are referred out. Sometimes figuring out that the diagnosis is a rare zebra is the best part.
It also depends on what local practices are where you are working. If everything remotely interesting in your city gets referred to the academic center (even if it's not "complicated"), then that environment would not be a good place for someone in PP who likes a mix of things. When interviewing for a job, getting an idea of what range of cases/pathologies you will see is important. If they don't do the things you're interested in, or get enough variety for you, you need to keep looking.