I know nothing about pearltrees except that I get a ton of spam from them, claiming that I was invited to join by someone I've never heard of.
They sound like a linked-in wannabe. I don't like linked-in either, but at least they don't spam me.
This is my homepage.
s_d_gil
Pros
Best web homepage there is. I organize all my web activities in their own families on my tree. That alone is genius.
But then I get to view others whose trees are similar to mine, and see what they bookmark. I have found hundreds of sites I never knew existed, some that have become favorites, through this method of organization.
It is very special, and has increased my web enjoyment and efficiency immeasurably.
Cons
New iPad app is great--but they still haven't ported it to iPhone. I would LOVE to make PearlTrees my web portal on the iPhone as well.
Summary
I can't say enough good about this app. It is so intuitive you just start using it, moving your favorite websites around to fit the way you use the web. And as you organize, your trees get closer and closer to others' trees who think the way you do. You can view their trees, visit the sites they put in them, and "pearl" them if you like them.
I said it before. Genius.