OK, so I'm about six months late to the party, but my own MB arrived yesterday:
Couldn't be happier with it. I love the sound and build quality. The metal top and bottom and hard, rubberized side panels give it a very substantial feel. I think others have said that the knobs and sliders felt cheap, but I totally disagree. You want to feel cheap? Grab the controls on a Moog MG-1 and see how those feel!
My only knock on it is the keys, which feel a little cheap. They're made of thin plastic that's too soft, and the action is too light. I wish that it had harder plastic, semi-weighted keys, like those you find on middle-of-the-road '80s synths like the Kawai K-3. But at this price point, it's hard to complain, right? The arpeggiator is extremely powerful, and I really had a great time experimenting with it.
IMO, this synth is worth every penny (and more).
My wife came into my music room last night and could tell I was having a good time with this thing. She lovingly refers to my little studio as "Dracula's Castle," because of the dark, repetitive synth sound that always emanates from it!