I think hyphen only looks good if there is only one of it in domain name and it is fairly middle in the name, like "www.good-stuff.com" instead of "www.somehugeword-is.com".
Of course there are some exceptions too..

Also I think it is good to keep names fairly short and easy as someone stated.. if name is already long it wont look any better if you add 5 hyphens in there.