Now that I have my minis, I can confirm that they are "true-scale" 28mm for the most part (some non-human/vehicle stuff works either way). If you have anything for Infinity, they scale pretty well with that.
Next to 1st Edition figs they will look really skinny. They may look a bit small next to some 2nd Edition stuff (though they scale well with the plastics from the boxed set).
Either way, they look fantastic so far. I love 'em.