I asked a Swans fan about him when the rumor first appeared.
Good squad player for us that, bar a few *bleep*-ups (such as failing to clear against Spurs),has done the job when called upon. Can play either full back or even midfield (he started as a mid and was then converted to right back). He needs to work on his attacking side, he's a little too reluctant to push-up for my liking, but defensively he's solid. Put in a great ball for Gomis' goal against City. Apparently he was immense against Belgium (trust me to miss one of our most important games in our history...),but I feel he's a Championship/lower-table Prem player. How he would fare with a run of games and if he played in the same position (we switched him between left and right depending on who was available) I don't know.
As for whether he's better than Whittaker, that depends on what you look for in a full back. Whittaker is more of an attacking threat, but Richards is less of a liability at the back. He's certainly better than the £500k we accepted from Fulham though, I can say that much.