Don't think I am beating a 4/3rds drum because I don't actually use the system, I am a nikon user
the lens lineup is pretty good... especially if you consider the OM lenses that can be used (yes without autofocus)
http://www.4-3system.com/modules/lenses/
Olympus actually released the first constant f2 zoom lens in existence (35-100),
http://www.4-3system.com/modules/lenses/lens.php?id=15
Yes, it is expensive... but its something the other manufactures do not have and it would be great for weddings
yes, there are plenty of issues with the 4/3rds sensor (high iso performance is marginal, and dynamic range is mediocre)