3.5 stars.
Shades of grey has one of the most amazingly original concepts in any dystopian novel I have ever read. (The only way I could possibly describe it would be that people's ability to see colour is used as a replacement for social class.)
The most interesting thing about this book is that everything in the society Fforde has created feels kind of alien yet slightly familiar. However I felt I kept getting confused with the rules of this society.
The characters were just uninteresting, the only character I actually enjoyed reading about was Jane.
The plot was quite slow at first but it really got interesting halfway through.