Definatly have advantages,usually less expensive, most have a 50 year warrantee, hell the old one that came off of this place the guy said was from the turn of the century, They have great styles now, no storm damage, etc.....Just take a look at them.
the house im building will have a metal roof for sure. our barn was from 1901 and we just now replaced the roof and it wasn't due to the metal leak, but the wind had finally started to rip the nails from the rafters and thus causing leaks.