I have only tried one other blog site, but it is really just a bunch of free webpages (for businesses, people, etc.) that also has a comment section. I have gotten no comments there and have not really posted anything new there in months.
My opinion about SoulCast is, it is simple to use and does not allow a lot of useless clutter. It promotes conversation, not just voyerism. SoulCast proves the saying "keep it simple".
Probably the biggest selling point for SoulCast is the anonymous part. You can post anything you can think of. If our thoughts were suddenly audible, we would not want everyone to know they were coming from us. What we say and what we really think are not always the same in the real world. Here, we can say whatever we are thinking without the consequences we would face in the real world.