[curtis]

There's no taking away from "better than any launcher in history". On the other hand, the comparison to the Delta IV isn't as informative as you might think it is. Falcon uses kerosene for fuel and kerosene is quite a bit denser than the liquid hydrogen used by the Delta IV. Liquid hydrogen not only needs a larger tank, that tank also needs to be heavily insulated. One consequence of this is that you simply can't get as high a mass ratio with liquid hydrogen as you can get with kerosene. On the flip side, hydrogen delivers a higher specific impulse, so extra tank weight is offset by fuel that is substantially lighter.