My MacBook Pro's keyboard hasn't failed, but I know several people whose keyboard has, and I've had a few occasions where keys would become sticky for a short period.
"Apple has determined that a small percentage of the keyboards in certain MacBook and MacBook Pro models may exhibit one or more of the following behaviors", the company says, "Letters or characters repeat unexpectedly; Letters or characters do not appear; Key (s) feel "sticky" or do not respond in a consistent manner".
Last month, AppleInsider combed through a small and insufficiently representative fix record dataset to come to some tentative conclusions-namely that the butterfly switch-equipped 2016 MacBook Pros experienced twice as many fix events related to the keyboard (excluding Touch Bar repairs) as the 2015 MacBook Pros that had the older chiclet design. The so-called "butterfly" keys allowed for a much lower-profile keyboard with reduced travel distance when pressed.
Apple customers have been complaining about these keyboards since the company introduced a new keyboard design three years ago. The keys are said to fail if dust lodges into them. Nor did it say how the new replacement keyboards will remain error-free. Earlier this month, 9to5Mac had reported on three separate class-action lawsuits related to the keyboard problems. Its offer to pay for repairs to the keyboard already performed may affect these suits, but no settlements were announced today. And unfortunately, fixing the problem isn't easy; at worst, it can involve replacing the entire keyboard.
In the same vein, it is worth noting that, prior to the announcement of the program, repairs involved nearly exclusively swapping out the entire top case of the keyboard.
Apple forums are overflowing with reports of Geniuses who have told customers that Apple is "collecting data" on the issue. On the positive side, Apple likely chose the new design primarily because it saved space for other components in the machines, and some users feel that they're faster to type on than other keyboards because of the very shallow, clicky keys.
Apple said the problems involved only a "small percentage" of laptop keyboards.