I've used a couple of other animation programs, including Alias (a real long time ago, but still it is the industry standard), and I've taught animation, I wanted to say there isn't anything wrong with Posers animation tools, it is really just learning how to use them. As the rest of the guys have said, the problem is it is just hard getting used to spline averaging. The flow of this always seems to throw new animators off, as the animation often goes to places they know are wrong, but it is just the animation program following the curve from the points you set, it doesn't know that isn't what you really wanted!