I've got black, and it is a huge battle. I'm getting a detail today and I have no doubt that it's going to look dirty before I get the thing parked in my garage. I bought one of those California dusters and am hoping it will help for routine dust, but this late winter/early (snowy) spring has put actual mud and dirt and road salt all over the car and that duster is pointless to even try for that stuff. Anything but a thorough hand wash is also pretty pointless as even though it gets the 'chunks' off, there's still a film of dirt visible on close inspection that really takes away some of the shine.
All that said, I think that it's no worse than any other dark car, perhaps we just notice it more b/c of the styling and finish and newness.