Hi, last week I was shot my first wedding. I think, that it was good experience for me. There was a lot of different situation: indoor, outdoor, bright sun, dark interior, bridal white dress and bridegroom´s black dress which was hard to made good exposition.
Bride and bridegroom was my friend, and all day was very calm, and without some nerves.
What I can say ? If somebody ask you to take their wedding day, say "Yes." It will be good experience for you, as the same experience for me ;)