Strong side of this device is its solidness and good build quality, aside from the "Mute" button issue, which i explain below. It's bigger than i've expected. Pots are nice to touch. Headphone amplifier is loud and clear. I like the fact that volume control, output selection and "Mono" button are now within an easy reach of the hand. And the device itself also nicely decorates my work desk, giving it a bit of that analog, moogish style.
For me, the biggest disadvantage is that "Mono" button only works for main output and doesn't work for headphones. For me, this button was one of the reasons for getting such a device, because periodic checking of how your mix sounds in mono is a vital part of mixing process. As i work in the headphones a lot, during these periods, this factor renders the device almost useless to me. I believe that the description might be a bit more clear on this important factor.
Also, the "Mute" button have a different feel when you press it. It feels like it might have been installed under an angle and scratches the metal case when being pressed. I don't think i would be using this button a lot, so it's not a reason enough for me to ask for replacement, but it might be a sign that quality control on the assembly line might also benefit from a certain level of improvement.