Works great. Encoder demo here:
Sounds is great too.
I don't actually own a midi keyboard and I've been experimenting with my own teensy, atmega32u4, and joy2midi controllers for generating midi signals. Preview of one of the prototype controllers using a teensy 3.2 and a couple of mcp23017 (not shown is the sd card and oled display):
I'm cruising eBay for a relatively inexpensive midi keyboard too but haven't managed to win anything.