Stone Barb is in my opinion one of their very few succesful designs that would fit right into P&P. It's essentially one of the first "real" tanks in a D&D game I can think of, in that it can actually tank hits and sustain frontline action in extended fights.
It is, however, quite a bit overpowered compared to the rest of the game's roster, especially in terms of tankiness. Barbarian's damage resistance is already one of the best abilities in 5E period, and Stone Barb abilities all synergize directly with that damage resistance, increasing the value of an already extremely potent ability. Considering the game is already too easy, that will probably keep me from playing it again. But it is an excellent design in my opinion. In a custom module or P&P game designed for that level of character effectiveness, it would be a blast.