We're happy to roll out the MIDI Keyboard Controller category for user reviews. Until now, MIDI was mashed in with the Synth category. Eventually we will add many more categories, including Drums/Percussion and Computer Audio Hardware, with sub-categories to follow.
The existing MIDI controller reviews will live in the Synth category for the time being since it's a manual process to move them over to the new area. Going forward though, please add any MIDI keyboard reviews to the new area.