I like the rule. I don't like that the umpire has to be 15 yards from the LOS. It seems to me that about 8-10 yards will do fine, especially if he is offset a bit from the center. The rule takes away another play-affecting factor too. You really want minimal external interference on the play.
It's time a rule came around that benefits the D a little bit. The rule makers have been putting handcuffs on the D over and over now for quite a while. As far as Manning complaining about it ... well, the other QB has the same problem.