The Overlord wrote:
Were the Son'a supposed to sympathetic or just evil ...
A bit of both, the Sona were the evil bastard who were going to provide the people of the federation with a wonderful omni-medical treatment.
Don't get me wrong, the Sona cared nothing for the huge number of people who would benefit from their actions, the Sona were basically thinking solely of themselves first, and a little revenge upon the families who cast them out second.
Inspite of that billions and billion of people across the federation would have had their lives inproved.
(Until Picard started making decisions for the entire federation all by himself)
And that decision directly contradicts his actions in Journey's End.