I've been gifted several times with "Beer of the Month" memberships, and always enjoyed them, although I wouldn't pay for one myself.
First of all, you typically do not get 12 different beers in a shipment. In several different clubs I was shipped 3 bottles each of 4 different brands. And I will say, the choices were always outstanding, and almost always from breweries that had no distribution in my locale, so the novelty factor was high. I tasted some brands, and a few styles of beer, that I might otherwise have never tried, like... I dunno... oh, milk stout, that was one. Interesting, glad i tried it, don't need to do it again.
Now that the craft beer revolution has engulfed us, however, I think your money is better spent on mix and match 6 packs from a better merchant. Heck, I even have something like 150 different beers available on sale at the supermarket!