He most definitely will NOT iron your shirt, but will be happy to take any ironing to the laundry where, for a nominal charge, they will do the ironing and then have it delivered back to your suite.
Your butler will (upon request) pack and unpack your suitcase, arrange for your shore excursions, serve afternoon tea and canapes from a rolling cart, serve evening hors d'oeurves the same way, arrange to have any problems in your cabin either fixed or replaced, arrange for housekeeping to fix or mend any missing buttons, take shoes away to be shined, bring you an evening cocktail from the bar, deliver requested VCR tapes or board games from the library, print out and deliver invitations to fellow passengers if you should choose to have a party in your suite, facilitate such a party by bringing in cheese, crackers, potato chips, glassware set-ups if you are serving drinks and, last but not least - serve any meal you desire (breakfast, lunch or dinner) in-suite. He will serve dinner (and only dinner) course-by-course, as they would in the dining room.
Give your butler 1-2 days notice if you plan to throw a party - as for dinner in your suite, let him know that morning if you wish to eat in. He will bring the regular dining room menu for you to make your selections.
In general, the thing to keep in mind is that the room attendant's job is to take care of your cabin, and a butler's job is to take care of you.
Hope this helps.