Nope, unlike most other overrated pokemon, Charizard's gotten so much backlash and hate that it's not really reasonable to call it overrated.
Blastoise does not get even a smidge of hate compared to the sea of love. It's overrated as hell. I like it. But it is still overrated.
Seriously, look anywhere on the internet where people are talking about pokemon. There'll be loads of Charizard hate. I also did a poll a while ago on what people think of Charizard, it had a fairly normal distribution, which a slight positive shift because well, people aren't generally hateful.
Not changing this sig until we get a new main series Tales game released on a Nintendo console in the US