I've heard good things, though I'll be waiting until Cataclysm itself drops before I roll a new worgen hunter I had planned to experience the new leveling experience. I did Loremaster on my main when he was horde side before I server and faction changed about a year ago and had never bothered to redo all of the Alliance quests, so the loss of those doesn't bother me, but I can see how others who lost a bunch of them would be miffed. But on the whole, Azeroth really needed this reformulation, so I imagine it will be a net positive.