I have to agree with the first poster P7 rocks.

I am still gettign used to layers and it is a very powerful feature for animators.   A tutorial would be nice but what I ahve learned so far is great.

The morph tool is very easy and also very powerful.

I have no out of memory issues.  

The preview mode is much improved.    

I haven't even started using the universal poses.

I only use P7 and won't go back to P6.   IMO This is a huge step forward.