Celebrity, MSC, NCL butlers are hit or miss. Have done all 3 and have had hit or miss on all. Our most recent MSC was great! Our most recent NCL was good. Our most recent Celebrity, terrible.
With Celebrity we felt it was lack of training. On NCL it seems to us that they are just generally not the best of the best of in this role. MSC I feel prides themselves on the butler service more than the others. (but our 1st was a bust, so we are 50/50)