This doesn't seem uncommon these days, but remember that Naoki Yoshida built A Realm Reborn back up from Final Fantasy XIV's initial disastrous launch, and much of this was done through treating players and purchasers with respect.
Yoshida took blame and offered solutions in a long forum post. Those who feel compelled may ask for a full refund (do that here if you bought it direct from Square). Yoshida pins the main issues on, "the significant discrepancy between the performance of the product our development team produced and the expectations our customers had for it," because "we released incorrect requirements, which were not updated prior to the Mac version’s official release."
The Mac version also release early, "due to our miscommunication with retailers," so, "some customers were able to download and play a pre-release build which suffered from performance problems."
Sales of the Mac version have been suspended until Square Enix can make an announcement that includes, "detailed information on the product, system requirements, and screen resolution." Not a bad way to handle the botched launch, all in all.