The expansion is absolutely fantastic. One of the great attributes is that it not only enlarges the breadth and depth of the game, but does so in a way that feels true to the original. This doesn’t turn Alchemists into a whole new animal, but merely takes the existing creature and gives it new bionic parts so that it can have superhero adventures. If you like Alchemists, then this is a must have expansion.
I don't believe there are gamers that casually play Alchemists; the game is outright obsessive. Having said that, I can't imagine why anybody who already knows and appreciates it will not own the present expansion. It's a straightforward must-have, and that's a hard fact. There's nothing one can do to debunk it.