Princess offers a unique service, I'm sure it will benefit a few...but maybe not the majority. I for one, don't want my luggage out of my sight.
There was one cruise a couple of years ago, that I wanted to ship one piece of luggage, for a family cruise. I called Celebrity and they adamantly told me, "No!" Thinking there must be a work-around, I got the number to the pier we would embark on Celebrity. I called the Celebrity representative, I think maybe even the Port Manager, and was told, "No way!"
I like the idea of one poster who advised to have it sent to your hotel, if you're doing a pre-cruise.