Quote - Someone will evetually copy and paste this anyway.  ;o)

Here is the list given by Steve;

Support for multi-processors and hyper-threading at render time.

New asset management dialogs that actually allow you add and delete folders as you wish, bypassing the limit of 13.

The ability to convert booleans to mesh and import/export them in and out of B6.
-Limitations - No infinite planes and metaballs (or items based on metaballs, such as trees from the tree lab), nor lights and cameras -- however, everything else is fair game!

Lighting via HDRI image maps in the Sky Lab.

The improvements to the link between Bryce and DAZ|Studio. Now, any animation you can create or import into DAZ|Studio can be added to your Bryce scenes by the same simple import mechanism.

Terrain editor - custom brushes! B6 comes with a few basic presets for new brushes types, and then Create your own brush shape from whatever image, whether it be grayscale or not, B6 will convert your image to a new brush with which you can edit or create terrains to your liking.

Random Replicate tool.

Support for 16-bit grayscale images in the Terrain Editor.

The re-vamped and re-categorized content directories.

Smaller compressed BR6 scene files.

The ability to add a texture to the moon.

Many bug fixes, such as the proximity bug with metaballs and trees that's now fixed, and the ever-dreadful "Top file menu being permanently hidden" bug now fixed.

The ability to export boolean objects as meshes sounds awesome, dude! Lots of folks have wanted that capability.