In all honesty, I was always angry with the phasing aspects in parts of Icecrown. It bothered me, especially when trying to summon guildmates to Icecrown Citadel for raiding, simply because most of my guildies weren't in the same phase as i was.
However, after seeing the videos from John "Totalbiscuit" Bain, I feel that the phasing aspects in both the Worgen and Goblin starting areas give it a much bolder, grander appearance. Not to mention that, overall, it helps to tell a much richer story.
Oddly enough, because of this, I kind of hope that more phasing is used, but only if it helps to create a bigger picture. Cataclysm has certainly captured my interest.