I would disagree with the sentiment that the latest nerfs reduce the efficacy of priests below where they are at currently. WotLK finally assigns a real purpose to the Discipline tree that it's lacked since the Classic game -- instead of just being a point dump for mana efficiency talents for Holy/Shadow, Discipline is now a full-fledged healing spec that plays differently from Holy.

Holy priests are the kings of group healing, beyond simply CoH-spamming. Shadow is getting some nice new tricks, but the VT nerf (as part of the change in raid buff mechanics) was necessary and there haven't really been any definitive numbers by anyone that Shadow DPS is being appropriately upped to compensate.

Repeat the mantra with me: "This is Beta. We shall see."

If the rollercoaster ride of beta changes disturbs you that much, you can always ignore it and stick with playing the live game until the change comes. For me, being a game designer means I like watching development in action, and I can think of fewer games with a development cycle as open and complex as WoW.