Compared to In-N-Out, Whataburger definitely tosses more food at you. The double burger is a solid 150% as big as the equivalent at I&O, although you do pay a little extra dough for that extra beef (or mystery meat, however you prefer to think of it).
I still don't like the fries. But they made up for it by actually pushing in the buttons on our drinks to indicate which was Coke and which was root beer! I don't believe anyone else has ever done that for me, and it felt special.