My DD is a 26er. Math is not his strong suit compared to other areas. Concern over the rigor of math and hard technical stuff gave him pause. He seriously leaned toward taking a full Army or Marine Corps scholarship at a top civilian college where he would never have to take high level math and science classes. I posted some questions about the math courses to this forum and got lots of encouraging responses, this eased his mind, he accepted his appointment, and things are going well. I was grateful for the responses as I think it helped him push the button and I think he's definitely where he is meant to be. The STEM stuff is a grind for him but he's making it. He says Arabic is worse.
One thing: They've changed the Calc curriculum pretty substantially from traditional Calc to make it more applicable to real life. This is confirmed based on what has been written on other posts and his experience. He described as more like Comp Sci than what he expected Calc to be like. He did fine. Says Calc II is pretty much just a continuation with a little more complexity.
I think there are plenty of math geniuses USAFA that can manage advanced math easily so it's really up to the individual. For those of you that don't fit into the math freak profile like my son, take heart, if you got in, you can do it. Oh, he also bombed the placement test.