That doesn't mean it's overrated, because it's not. Yes, the system is stupid, but that doesn't make grammar schools overrated. They are not the be all and end all. If you're smart enough to understand that you perhaps were not in the best position to sit an important exam at age 11, then it's highly likely that you, at this age if you try hard enough can reach the skill level of any grammar school kid. I don't know your age or situation, so it depends.