Some questions to cleanup my first PCB
I see a couple of serious problems here.


The footprints you're using for diodes and resistors don't look right, unless you plan on mounting all of these components vertically. (And even that might be a tight fit.) Use horizontal footprints for these parts.
The footprints you're using for connectors look like large terminal blocks, designed for high current devices. Check the size on these, and consider using a smaller 0.1" spaced connector, especially for logic-level connections (like MIDI).
A lot of nets are routed long distances around pins or other nets rather than using vias, and I see at least one disconnected net under U1. Once you've changed the footprints for your diodes and resistors, move some parts around and try to clean things up a bit.