Many, many chinchilla owners use ferret nation cages including myself, and love them. With a few simple modifications they make awesome cages for chins. We have a huge thread going on with pictures of what people have done with their Ferret Nations. You can check it out here: http://www.chins-n-hedgies.com/forums/showthread.php?t=134
I don't have one myself but if I could I would have tons of them. I think they are great for pet owners. some people would say they prefer other cages but I think they are nice. I have several custom made melamine/wire ones and they are great but I would not do melamine again - just too stinkin heavy and I like the ability to be able to attach things to the wires.
Some people would say they like the critter nation (think thats the name of it) because its wires are horizontal vs FN that has vertical bars.
The good thing about the FN is if you wanted to have more than one chin you could always divide the cage in two if they didnt get along and make two cages (top half and bottom half).