My friend has one of these and I bought it on his suggestion.  It works pretty well.  I have a garden that is over an acre.  77 rows, most of which are 200 ft. long.  If the ground is loose, it is wonderful.  My problem is that a lot of my garden is mostly clay and makes rather large clods.  The seeder is hard to manage over rough dirt, but still easier than sowing by hand.  I consider it to be a time saver and worth the money.