I still use Poser 6. There wasn't much in Poser 7 that enticed me enough to upgrade.

The morph brush looks interesting, but I don't do my own morphs so it wasn't something I really needed. 

Poser 7 can use HDRI lights.

It has an "undo" feature, which is a real memory hog, so much so that many are turning it off completely or lowering the amount  of "undos" to just a couple.

There are a couple more nodes in it that Poser 6 does not have.  While I love the material room I am not that adept at making my own shaders so I use what other people make or their examples and so far I haven't had any issues with "missing" nodes.

There might be others, but those are the only things that I can recall off hand.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi