If you try the snapshot, be sure to back up all your worlds. Seems its corrupting a lot of peoples maps.
Yeah, the Enderchest's will probably be more useful in solo games. But aside from mini PW setups, it'll make doing trades between players a lot easier. Just both of you stand next to a chest and pop your trade items in.
Oh liquid dispensers. Can finally make me some traps.
Also apparently Emeralds are found inside the larger mountains.
Here's a video of all the new features. Looks like you're safe Owain. Its only small pyramid/temples. Be careful of this part of the vid though, as it spoils a temple surprise.
The trading system looks like fun.
Oh, theres a 'b' version of the update now. It changes the menu system in Creative mode, and Emerald ore is now green.