I consider Bryce to be a superb program for producing still images but I have never taken the motion features seriously. Bryce is great for stills, but I always thought from the first time I took a good look at Bryce 3.1 that the programming effort put into adding animation features would have been better used to speed up rendering and fix bugs. Put all that effort into still images and you'll end up being able to produce lovely images, but however much effort you put into Bryce animation the results will be less than your talent deserves.