Everyone going the SAP route, whether sponsored or not sponsored, should ask themselves at least three questions. First, will the SAP program help me address a deficiency in my application. Second, if I successfully complete the SAP program will I have substantially increased my chances of admission. Third, if I am not admitted after completing the SAP program what are my options.
Sponsored preps can easily answer the first two questions with a yes, and assuming they successfully complete the program will likely never get to the third question. It's not the same for non-sponsored preps, especially those hoping for admission to USNA. The size of the USNA sponsored prep program appears to have been shrinking over the past few years. This past year, there were only three sponsored USNA preps at MMI (I believe all were admitted to USNA for 2015). There were far more USMA, USAFA and USCGA preps at MMI.
Our DS attended MMI this past year as a sponsored Falcon prep. MMI has a great, great SAP program and it will help you address academic and test score issues, and will also help you demonstrate to your chosen academy that you are serious about attending a service academy and won't back out. BUT, you must keep in mind that there very well may be non-sponsored preps (no matter what prep school they attend) that are not admitted to their chosen academies even if they successfully complete an SAP program.
The MMI faculty, staff, Col. Lewis and President Mollahan are totally committed to helping you succeed. They are accessible, interested and seem to truly care about all the students. They will know your name and why you are at MMI. But they cannot work miracles--the unfortunate fact remains that in the academies' eyes the sponsored preps come first, non-sponsored second. Makes sense--if someone is paying for you to attend a prep school, they have a vested interest in your success. (And, because it appears USNA is at the low end of prep admissions, if you are willing to attend one of the other academies you absolutely should apply to it as well as USNA while you are at MMI.)
As for Marion, it is a very small town with little nearby. There are a couple of fast food places (Hardees and Subway), the usual Chinese and Mexican restaurants, a food store, drug store and not much more. However, this can be an advantage--you will spend most of your time on-campus bonding with others in your Company and focusing on academics except for occasional Friday or Saturday nights when you can go to T-Town (Tuscaloosa) or Selma if you have a car or know someone who does. On some weekends you might even make it to Gulf Shores or Pensacola, but that is rare.
As for the MMI experience, you will take the same courses as those at the USNA take their first year. Your MMI professors will write recommendation letters for you, as will Col. Lewis. You will attend an SAT/ACT prep course on-campus. You will retake the SAT and/or ACT, perhaps more than once. You will wear a uniform every day, clean your room and the bathrooms and be subject to inspections, learn to march and parade, be restricted to campus on certain days, and observe a chain of command. The cafeteria food is mediocre but generally tolerable, and the weather is, well, it's Alabama so you can expect heat. The dorms are undergoing renovation and are air-conditioned, but it certainly isn't a hotel. Living conditions are spartan--exactly what you will get at the academies maybe even a notch lower. There is a nice indoor swimming pool that is opened to the cadets a couple of times during each week, and there is a renovated weight room with enough equipment to keep you busy. There is also a golf course adjacent to the school, a baseball field and a track. The campus is compact, so you won't have a long walk to classes, the gym, pool, library or the cateferia. During holidays, MMI arranges for a shuttle bus to take cadets to/from the Birmingham airport so that they can get home and return to MMI. You will mature, grow and develop lasting friendships at MMI.
Having said all that, I can tell you that our DS received from MMI the best possible preparation for USAFA. He would choose to do it over again in a second. He is confident, mature and as ready as anyone could be for BCT and the Academy. MMI did this for him, and it might very well do it for you, too. Just be sure you are realistic about the possible outcomes.