DAZ3D is giving Bryce 5 away for free. It's a time-limited offer, so get while the getting's good.

I gave it a spin last night at it indeed seems to be the full-meal-deal. Very attractive but somewhat bizarre interface. They have a pdf version of the manual for Bryce 5.5 available for download, and I had to get my hands on that before I could even find the main menu.

I personally like Terragen better for landscape generation, I find it more intuitive and I think the results are closer to photoreal, but there's no doubt that some very nice work has been done in Bryce.

For those real 3D enthusiasts, Daz3D also offers very powerful, free software (DAZStudio) for character and figure generation.