I found these stories mostly disappointing. I would have tossed the book away halfway through, but it was the only available reading matter during a boring wait, so I persevered. My perseverance was not rewarded.
Most of these stories are just achingly clever in conception - what I gather the film world calls "high concept" - but they are emotionally empty, or intellectually empty, or sometimes both. They are mostly the kind of clockwork stories that a bright student in a creative writing class will produce when under deadline pressure - as I know from personal experience having written several of the kind myself. Gotta get something on paper, anything... and finally an opening sentence or an image comes to mind, and you push it as far as you can, using verbal and narrative tricks to hide the fact that you haven't a clue in heck as to how this situation could ever arise, nor what to do with it now it has arisen.
For an example I will cite what is undoubtedly the best of the stories in the book, David Levine's "Nucleon," which also won a prize and appears in Hartwell's Best of the Year. A conceptual artist discovers a wonderful scrap yard run by an amazingly cute & insightful old-timer. The yard always seems to produce exactly the object the artist needs; it even turns out to contain a highly rare and reminiscent object from the narrator's childhood - helping him, possibly, reconcile to his childhood. Or not, it's all quite fuzzy. Then the lovable old-timer dies and wills the scrap yard to the artist, who suddenly finds he has acquired the amazing talent to lead others to exactly what they need to find the yard.
See what I mean about "high-concept"? There are lots of clever turns; the artist's creations have evocative titles that make us laugh and there are fun bits of trivia about old artifacts. When it's over, though, and you sit back and think about it, the story is about nothing at all. It's cotton-candy fiction, hermetically closed off from any real emotion or character development; no resonance with any human's real concerns; forgettable.
And that's the best of the lot. Second best would be "Flowers from Alice" by Cory Doctorow and Charles Stross. It has some of the bite of good SF; at several points you find yourself nodding in surprise, thinking, oh! yes!, that's possible, that's how it could be! But the final twist, one, caused me to lose sympathy with the character (his troubles are all of his own making), and two, made me realize how John Varley had rung all the same bells much more melodically.
The rest might look good in the creative writing prof's in-basket, but wouldn't (I hope and trust) make it past the slush pile of a decent magazine. In sum, don't spend money here unless you have a LOT of time between flights at DFW.