We are not doing it. I really really considered it because it makes a lot of sense logisticly but in the end decided we wanted to go the traditional route.
I think it's a personal decision that only you and your groom can make.
You can't go wrong either way, the first moment that you lay eyes on each other on your wedding day is going to be special and meaningful no matter how you choose to do it!
My fiance and I just went to a wedding this past weekend where they did all the formal shots in the church before the ceremony. I'm sure it saved them time and aggravation, but we didn't like that we could see the bride before her big entrance at the ceremony. All the guests could. It took away from the ceremony itself. I would just say if you are going to do it, don't let all your guests see you before your big moment walking down the aisle.