I tested darksend today!
I must say, I like it that you can premix your coins and then use that "dark balance" for sending anonymous transactions

Pretty impressed by the GUI as well.
My only remark (also related to the thing below) is that it took nearly 3 hours to mix 2 DASH... That seems a bit slow, but hopefully if we get more masternodes online, that won't be an issue anymore. But I'm willing to wait a bit. Privacy has a price, in this case it's waiting time.
Someone correct me if I'm wrong, but isn't mixing slow sometimes because of a lack of people mixing, not the number of masternodes?