I enjoyed this novella a lot. Its a well thought out exploration of a possible near future, in which a start up company creates "digients" digital sentinents - virtual pet/companions that can learn, and offers them for sale on an online platform. The story of how the digients learn and grow and interact with the people who buy them and the company who sells them is very concrete and grounded in the way technology companies and on line communities work and act in the present day, and its fun to see that all worked through so believably.
At the same time the story opens up a whole slew of very interesting questions about how people might interact with artificial intelligences; selling them as companions, getting bored with them, bonding with them, feeling responsible for their development, wanting them to work as personal assistants or sexual surrogates, getting into fights with their famlies about spending too much time with them, feeling guilty about neglecting them.
Its a novella, so it doesn't always come to conclusions on the very interesting questions it opens up. But in a way I think that's probably better. He sets up the questions in a believable, interesting way, and then leaves it up to the reader to think about them. Nice.