I absolutely agree on the battlemaster comparison. No one wants another subclass that has little use, and comparing RK to the worst or incredibly narrow subclasses will result in another dead subclass.For all the people suggesting the Rune Knight be dialed down... let me point you at the Arcane Archer. A Fighter subclass with severe use limitations on its special abilities that's widely considered somewhere between "too restricted to be much fun" and "so weak it's complete garbage". The Arcane Archer is what you get when you're too stingy with a Fighter subclass abilities.
So what I'm saying is, I played a Rune Knight in one adventure, and it was in no way overpowered. Granted I wasn't trying to minmax my build, but still, it's no Loremaster. I highly recommend people give the Rune Knight a fair try as printed before they nerf the hell out of it, and that you consider Battlemaster your benchmark rather than the Arcane Archer.
I'm thrilled that this class gives non weapon damage options, tons of flavor and modular options.