Blakcbeard has been a flop as far as I'm concerned.
Yeah, he will be Luffy's final enemy (or one of the last 2). Is portrayed as a wall that Luffy can't overcome until finale etc.
But the dude is too clumsy in CQC (takes hits that he shouldn't), gets shocked by everything he sees etc.
I like him due to what he represents (one of the few true pirate-like character), want to cheer for him. But I don't get the energy from him required of one of the series final antagonists.
Be honest and compare the intro Blackbeard ("people's dreams never end") to what he is currently in manga. Quite sad.