What I learned from Medical School (and a Primary Care-oriented school at that) is you treat all walks of life, no matter where you are. Even in rural MS. However, your diagnoses will start running the same. What I saw a lot of was diabetes, CAD, post-op heart attack, etc. Things that can be associated with obesity and poor management of health. Mostly follow-up with the PCP, but the FM was very involved with the treatment plan. Most see this as mundane treatments and saying the same things over and over... and over and over again; things like "Stop smoking, eat healthy, get 30 minutes of exercise every day, and reduce salt intake." But that's true with a Cardiologist, Neurologist, and so on. Your patients, if you choose to make a little more money and work in rural areas, will have sort of the same problems. But once again, that's just about every field other than surg.
Are you gonna see horrific traumas and make split-second decisions? Most likely not (unless a patient comes in with a trauma because s/he can't find a hospital.) Mostly these doctors went into it because they 1.) have ties to the community or 2.) want an easy practice, great pay, and work 8-5 workdays with some weekends. This depends on where you work, how many patients you have, how many doctors are in the town, etc.
P.S. non-compliance is going to make you wanna scream at your diabetic patient 2 steps away from going into DKA. It's in every field, but in FM, your patients will most likely be in the lower class whom are either 1.) uneducated about the importance of treating his/her illness or 2.) don't have the $$ to afford the prescription.