Bryce was very good at the time of first release, and so much more than just a landscape generator. At the time, I worked as an illustrator for a newspaper and used it on a daily basis. Not only for making landscapes, but mainly for blocking out illustrations, which went very fast, and for texturing and rendering. By today's standard it was of course quite limited, although, as Was says, it had some great features, such as volumetric textures. I used Bryce together with FormZ (for modelling), Photoshop and Poser. Even though rendering at that time was slow I could create anything I wanted; if you do something very often you will find a workaround for everything. Sometimes I yearn back to those days, so I definitely have a soft spot for Bryce as well.
A few examples of what you could do with Bryce.
A. The egg is a terrain, the yolk a sphere.
B. The graphical hatchings are Bryce textures.
C. Texturing ice cube done in Bryce.
D. The moon is a terrain, painted in Photoshop and displaced in Bryce.