Hey there -- it looks like you've done some nice 3D work there!
My first thought was regarding the span of the desktop because I don't see any support structure holding it up in back. An 88 key controller on or under a span that long could cause some serious sagging problems -- especially with the notch cut into it for the monitor... Did you consider this in your design?
Also if you're going to put the controller under the desk, be sure the desk is high enough to work with. A typical desktop is about 30" high, but the keys of a piano are typically a lot lower, so it does make sense to have the controller under the desk -- just be sure you have enough room for your knees under there, too.
I've never had monitors positioned vertically. I have three all side-by-side and that works out pretty well for me. It seems like it's easier to move my head side to side then up and down. (Maybe I'm just used to saying "no" more than "yes"

) It does look cool, though.