I think it's the best messenger I have used all around, in terms of UI. I particularly like their take on the verification levels using a traffic light metapho

I think it's the best messenger I have used all around, in terms of UI. I particularly like their take on the verification levels using a traffic light metaphor - giving visual feedback on how well trusted a contact is on my list; I wish other clients would adopt it something similar and encourage more people to verify keys out of band.