I actually purchased Bryce 5.5 earlier this year and worked wih it for 4-6 weeks before abandoning it. It does have some nice features and does some things much easier than Carrara. However, I abandoned it for 2 reasons. First, because of the texture engine, which seemed seemed to be too much of a hit or miss affair (or perhaps I was just unable to figure it out). The other reason was it was no better than Carrara (C4-Pro version) in the things I was hoping to use it for, primarily skys and clouds.

As Hoofdcommissaris points out, Bryce is built for landscapes and there are people who have done some marvelous work with it. But as an all around tool that does everything in one package (modeling, texturing and rendering), Carrara is hard beat.