Cosmocopia is at once strikingly original and faintly familiar. I don't recall reading anything else by Di Filippo, and this book was originally published in 2008. I can't pin down another story along these lines, so the familiarity is a mystery. The more I think about it, the more I think I've read something similar, though.
Our painter-protagonist travels to another universe, and Di Filippo does a great job of establishing a world that's just similar enough to be a credible next-door dimension, but just distant enough to be bizarre and curious. He establishes the environment beautifully, making weird creatures and culture credible and suggesting a fully realized background. It works perfectly for his story, the bulk of which takes place in this secondary world.
The ending of the book is weaker. While the final segment starts out well, it devolves into a an ending that doesn't make a great deal of sense, and hints at a cop-out. Di Filippo finesses this a bit by focusing more on the characters than on the grand mystery the story presents, but I still found the resolution to be a let down.
All in all, an original and interesting story well worth a read.