I think the coffee that comes out of single-serving coffee pod machines is not very good. But, putting that aside, it's obscenely expensive, as Oliver Strand points out in the New York Times:
For example, the Nespresso Arpeggio costs $US5.70 for 10 espresso capsules, while the Folgers Black Silk blend for a K-Cup brewed-coffee machine is $US10.69 for 12 pods. But that Nespresso capsule contains 5 grams of coffee, so it costs about $US51 a pound. And the Folgers, with 8 grams per capsule, works out to more than $US50 a pound.
Not to mention the steep environmental costs that come along with chucking hundreds of millions of plastic capsules into the garbage.
There's a much better way to use a Keurig, actually -- the reuseable My K-Cup lets you brew your own coffee in Keurig machines, so at the very least you have fresher coffee that's cheaper, and there's nothing to throw away after every cup. [NYT]