I don't think Harry Maguire would have been called up to the England national team if he was overrated. That's why it might be a bit harsh to say it's exaggerated. He definitely has talent and it wouldn't be right to claim otherwise. However, he is very error-prone and this causes big problems in the teams he plays for.
It's really a big joke if someone think Maguire is playing because of his big name, he should become a brand ambassador if he's a bad player. People always forget 1000 good deeds for one fault, so that's why vast majority think Maguire is a bad player.
Maguire is a good player, he good in build up since he has a good long ball pass accuracy and clearance.