Pros: Tiny, no USB cable required, great sound, easy setup and ASIO4ALL compatibility
Cons: None that I can see
I'll update this once I get my UM Miracles back to really put it through its paces, but the Dragonfly sounds incredible driving my BeoLab 3 (active) speakers.
Super easy setup - literally plug and play. I'm using it with ASIO4ALL and it blows away any other USB-powered DACs I've heard. Connected to my BeoLab 3s it's easily on par with my Audio0gd NFB-5.2 in terms of soundstage and transparency.
More to come when I can drive some IEMs and headphones with it