Disunited is a lot shorter than the last couple of fantasy (virtual) doorstops from Tor, and that is commendable. The plot is straightforward: alternative timeline travellers get stuck in an America that never stuck together, lots of little states bickering over borders. If you know your US history this might be a lot more intriguing than it was for me. It would make a great alternative textbook for kids at school.
It is set in 2092 or thereabouts, but I can't quite work out why. There are no great leaps in technology, apart from the mcguffin for travelling to alternative timelines. People still use cellphones, PowerBooks (obsolete already), and drive cars that run on petrol. It could easily have been set now.
Less annoying than a lot of books, not as interesting as some books. A middle-of-the-road, ho-hum, nothing else is on so I'll watch this, kind of a book. The literary equivalent of watching "The Wedding Planner" on TV. Again.