I am not sure if you can sue or not; if there are specifics stated in the contract, like lets say it states that he guarntees 30 pictures of the bride and groom and you only received 20 pictures, then you most likely could sue - but if the contract didn't state specifics than it is going to be harder.
That's horrible that you didn't get the service/quality of work that you looked at in his portfolio. You may be able to report him to the better business bureau. You also need to talk with him and tell him you are unhappy - see what he is willing to do for you. If he isn't helpful then you can decide how you want to proceed from their.
Also - should you decide to take this case to court it's a good idea to go to his website right now and take some print screen shots of the site and his work. If he knows he is going to court he might take the website down or change the look of it.
I'm really sorry that you didn't get the pictures that you wanted. It's unfortunate and I think it is a horrible thing to do to someone on their wedding day knowing that it's not something you can just "do over."
However, in order to get some nice shots you could dress up again and go to a studio. This way you will have some nice shots. It's also possible that someone might be able to touch up the pictures using photoshop. A professional can work wonders with it. My friend, who is a photographer, is amazing with photoshop - so, if you wanted her contact info she might be able to help.
Good luck to you!