4.33 is a meaningless number standing alone. It may be great on a 4.0 scale, but USNA will take into account strength of schedule (heavy STEM curriculum), strength of school, SAT/ACT scores and your teacher evaluations. There are lots of variables to take into account.
In addition, keep in mind that 4.33 might not be that great if those you are competing with have a 4.4 , or if they have other things in their application that make them stronger candidates. At the end of the day, USNA 's mission is produce Naval Officers. Sure , they need to make sure that any applicant/appointee has the academic chops to get through the program, but there are alot of other factors that go into deciding who will be a good Naval Officer.