If you start the clock at the aquisition of Danger back in 2008, it took Microsoft more than two years to deliver its failure. In that same period of time, Apple and Android have delivered several generations of useful and functional devices. So although Microsoft pulled the plug quickly on Kin once they realized its failure, they wasted two years; that's not failing fast.
So let's look at the "fail cheap" angle. Microsoft didn't reveal the price it paid for the privately-held Danger, but it was rumored to be $500 million. Then there was the cost of the two-year-long development effort, which at this point seems like a total loss of both money and opportunity. In the post I linked to above, note the final sentence: "Given that there are a couple of devices already on the market that use Danger software (unlike Android's prototypes), Microsoft might actually be able to get some disgruntled Android developers switching to its platform." Oh, the false optimism of 2008.
Microsoft's death notice for Kin puts the best possible face on the fiasco, saying that it was integrating the Kin team into the Windows Phone 7 team. Let's hope they learned enough about what they did wrong to prevent Windows Phone 7 from becoming the next of Kin.