Yes ork boyz are a weak unit but even that depends on size and circumstance. For instance a unit of ten isn't going to do anything but a unit of thirty can shread terminators and tanks. However, if they don't get the charge then they're quite easy to kill (speaking from experiance).Ork Boyz a weak unit?
They are one of the best units in the Codex. In fact, they are one of the best units in all of 40k.