If you love science, math, and engineering, then this is the place for you. I was never interested in any of those subjects, and am currently an economics major, but still have to take many required technical courses. While calculus I is calculus I anywhere, it's still very different here at the academy. If you are very strong in math or science, the required courses will still probably give you a challenge. You must remember you do not have as nearly the amount of time normal college students get to study, so factoring a full courseload on top of a plethora of other activities is stressful to say the least.
As an Economics major, I feel I received an absolutely first-rate, well-rounded education that met or exceeded what I would have received at an Ivy League school. In 2006 alone Navy produced four Rhodes Scholars—more than any other university. Professors are there to teach and are very accessible. Midshipmen compete at academics in the same way they compete at sports (not in a cutthroat way), and the students who are excelling generally made an admirable effort to help those who were struggling. One unique feature about Annapolis and the other service academies is that they exist for the purpose of training and eventually "hiring" their graduates as commissioned officers following graduation. Because of the complexities of modern warfare and the need for technically adept Navy and Marine Corps Officers, all students (even English and Political Science majors) take a "core curriculum" that is heavy in science and engineering. In my later career as a lawyer, I found the type of methodical thinking these technical courses require to be very useful. My professors were also very supportive of my later efforts to apply to graduate school.