In defense of package bees - and I have installed many packages -
 
1. I often get a modest crop from a two pound package.
 
2. Package bees can be sent US mail across state lines.  Not so in
America with nucs.  You have to go get them, and many northerners don't
have a local source of nucs.
 
3. If you are concerned about the 3-week lag until the first brood are
hatched, consider (for those who have existing colonies) borrowing a
frame of brood from one of an established colony and giving it to the
package bees..  This works quite well.
 
Larry Krengel
Marengo, Illinois USA
Home of Dr. C. C. Miller