Neither of us have any issues with the keyboard other than the clearly above average failure rates and the hassle of getting it repaired. My 15" has not exhibited any issues at all, the slightly older 13" has started to develop some stickiness with the arrow keys.
Obviously there are issues with this keyboard and I eagerly await a redesign on it (as well as haptic feedback on the touchbar and making the touchbar option across all models).
On the whole I'm quite happy with the extended warranty as it essentially amounts to free AppleCare+, and given their insistence on making the overall device unserviceable it also amounts to a deductible free midlife battery replacement.
It's an elegant solution to the whole fiasco in my mind-- the cost of servicing all these keyboards has to be painful beyond normal for them given that ridiculous design, magnified further by the fact that end users should have no problems encouraging the keyboard to fail if/when they want a scratch free case or 0 cycle battery. To say nothing of how it undermines the value of AppleCare as a service, both because you can get nearly the same thing for free, and the existence of the keyboard program is straining their staff resources on repairs, which are otherwise almost exclusively devoted to AppleCare customers.
It is soul crushingly inconvenient and annoying when the keyboard breaks and you have to have it replaced.
I’ve had mine replaced twice so far both times under warranty. Because Apple provides the extended 4-year warranty for free on the keyboard it is no longer a financial risk to own the computer, only an inconvenience if it breaks again.
On the plus-side, because the whole computer is glued together I got a fresh new battery installed every time they replaced the keyboard.
However, the touchbar...still a pointless gimick.