I could argue either side of this.
The souls are good in a way, because they are trying to make earth better. Seeing what Wanda went through through her eyes made me realize just how hateful humanity can be. When the humans were trying to take the souls out of their hosts, I wanted to cry right along with Wanda. It made me feel angry towards the humans, and a little ashamed. Also, Wanda could not grasp the concept of hate, evil, betrayal, or disloyalty. Without having those aspects, how can you be bad?
On the other hand, what the souls did to the planets they inhabited was very destructive. They completely intruded on another species way of life for their own personal gain. Although they could not see this, they never thought about what they were doing to the planets they lived on, and the lives that were lost, or the devastation they were causing.
I still can't decide which way I feel more strongly about.
"For the dead travel fast."
~Bram Stoker's Dracula