Heavens door is the single most overpowered stand shown so far. (anime only, I haven't seen manga yet)
Change my mind
@Bunn0241 Yeah, when it comes to fighting, then obviously nothing beats The world, sexy pistols and other that allow you to one-shot the enemy before the fight starts. (without the obvious anime logic)
I was talking about the general usefulness, since Heaven's door allows you to gather a shitload of information, as well as completelly re-write mind on an enemy. That is OP as hell.
@LukeAlmighty I see your point. Heaven's Door is a really strong stand, but it highly depends on the range/location of the enemy stand user, and Kishibe's own reaction speed. It is pretty much overpowered only on first encounters which do not devolve into full-on fights, as the stand itself is not very physically powerful.
An example of a more powerful stand would be Highway Star, as it is extremely powerful, has both a long and short range version, and requires little to no input from the user.
Of course, Kujo Jotaro can also easily defeat him by stopping time with his super-human reflexes, even before Kishibe starts his offense.