Enjoy, have fun, I'll stick up some images for you to take a squiz at while you download it.
*sigh* Apparently I have to exceed 300 words in this post, so let's waffle on about what's in it:
New models - basically, it has everything barring the Hive Tyrant now
New animations - Raveners are fully animated, and there's a few other fun surprises
New ways of doing things - mostly you won't have to care about build zones anymore (mostly)
Plus other pretties.
So... go nuts. Eat some worlds.