It's a dream
I got this to replace an older controller keyboard that I had. What drew me to the MPK line were the pitch/mod wheels (my previous controller used a single stick type that I didn't care for too much), the fact it's one of the few controllers out there right now with aftertouch, and I had heard good things about the feel of the action with this controller.
After having used it for a while I can tell you some of the things I like and don't like about it.
First, the action on this controller has to be one of the best feeling I've used, especially for piano.
All of the controls are easy to use, very smooth and well built. The only problem I have at all is that I find the pads to be pretty stiff compared to what I'm used to. My understanding is that there is a way to modify them to be softer but I have not really looked into what that would entail. Really it's the stiffness of the pads that keep me from giving this controller a perfect 5.0 rating.