A niece got a 'professional' to do her wedding. The woman was trying to break into photography and her inexperience was obvious. She only had a 60D and kit lens, her battery went flat as the bride was walking down the aisle and the spare battery was in the car (at least she could sprint pretty fast!
), she didn't position people properly against the backdrop in the group shots and there were problems with the shots at the reception. They were glad I took some shots so they had something, but what can you expect from a 400D and 15-85mm lens? So, if you get a 'professional' get a professional professional.