I found a great article with some good information at weddingsolutions.com.
Things To Consider: Make sure you hire a photographer who specializes in weddings. Your photographer should be experienced in wedding procedures and familiar with your ceremony and reception sites. This will allow him/her to anticipate your next move and be in the proper place at the right time to capture all the special moments. Personal rapport is extremely important. The photographer may be an expert, but if you don’t feel comfortable or at ease with him or her, your photography will reflect this. Comfort and compatibility with your photographer can make or break your wedding day and your photographs!
HOW TRUE. As a photographer, I can’t put a factor on the importance of being relaxed. It’s certainly true that when either the photographer or the person being photographed is under stress, it shows up in the photos. Often times, with all the stress of that big day, relaxing is the last thing on the mind. Technical skill and creativity play equal parts of the finished photographs along with my ability to connect to the people I’m photographing. It always helps to slow down and connect. The art of taking beautiful photographs requires a little light and a little time. If your photographer is “on-top”, you can follow his or her relaxing pace, enjoy your wedding, and have great photographs to enjoy for a lifetime.
The entire article can be found here: http://www.weddingsolutions.com/article/Wedding_Photography_1.html