The bagpipes produce room filling sound. If your wedding is in a church or cathedral the pipes will sound wonderful. If you're getting married in a little chapel or at a bed and breakfast, your guests may get blasted out of the room. In that case consider having the piper play outdoors, for example piping the guests into the building.

If the wedding is to be outdoors, no problem. If you're renting the Astrodome (I've met someone who did this) consider hiring a whole pipe band.

One other thing -- the drones stick up to about 7 feet for a 6 foot tall piper. Processionals or recessionals that go through normal size doorways can be a problem for the piper.

If the venue is a small space you can also ask if the piper can play small pipes. The volume is much lower. Ask for a demonstration to see if you like the sound.

Best of luck,
Clyde