Extremely unprofessional -- do not use them! \r
I went to a wedding last weekend as a guest and was just appalled at the photographer. He didn't even come, he sent his assistant, and his assistant showed up 15 minutes after the wedding was supposed to start. He took maybe 20 photos of the whole ceremony (all with bare straight on flash and lower quality equipment than most of my friends own), never even lifting his camera at anything other than the bride.\r
He was rather rude and unprofessional during the family posed shots after the ceremony and clearly had no real interest in doing it well.\r
At the reception, he showed up, took photos of the cake and then of the couple cutting the cake, and then left. No first dances, no bouquet toss, nothing. Including the break between the ceremony and reception (which was about 1.5 hrs), he was involved for about three and a half hours.\r
Your guests can take the same quality (or better) photos with their point and shoot cameras. If you are going to hire a wedding photographer, hire someone better.