• The first major issue you'll notice here is that your previous addons won't work in this patch - as previously reported.
• This one's for druids: Remember all those patch notes that the devs were talking about for your guys? It turns out that only two of them - Omen of Clarity and Swiftmend - were implemented. What's more, the devs say the notes were wrong.
• Regarding the new LFG function: There's a couple of bugs in this otherwise handy update; Higher-lvl guys seem to have probs looking for lower-lvl dudes for parties or raids.
• Rogues: The stealth animations were speeded up, which unfortunately makes your movement look like the "doing the pee pee dance." Good thing nobody can see you...
• Thrown items now lose durability when used.
• Due to the new updates, we recommend staying away from the battleground servers. Everybody's there to try out the new stuff, so they're likely to screw up. Enter at your own risk.

Via WoW Insider