I don't think that I have ever seen a Pixel Art calligram before - Very cool.
The message is a bit difficult to read on Mario's face and stomach, but setting the font color message darker that the surrounding nonsense-characters makes things a little better. The "sm@art#at+|those" portion is the least readable. I would consider making the "art" part of "smart" the same font color (the same as the rest of the message); this is the only place where you break with the internal logic of the design.