We've always brought our own hair dryer...ones supplied are to wimpy...BUT the ones on the Infinity were SUPER charged!
Don't know if any of the other Milli class ships have them...but our hairdryer really worked super well.
BTW: It's the hair dryer already hooked up in the bathrooms. Large boxy type thing. Our cabin also had a traditional type in one of the drawers that we never used.