EDIT (03/29/2009): I added some things from the issues discussed by other users as well as some things I remembered from my previous cruises.
Some tips:
1) If I remember correctly (and if that policy is still in effect), if the price drops, Royal Caribbean will refund you the difference. In this case, it will even work half-way into your cruise since it is actually two separate sailings back-to-back. So, if the price on the second "leg" drops while you are cruising around the South America, you will receive the difference. The first leg was $50 cheaper just a few days ago, so it may drop in price again.
EDIT: You have to call to request the pricematch. They will not pricematch it autoamtically. (I don't think I made it clear in the first revision).
2) Some people don't like days at sea. This cruise gives you a very good ratio of days at see. Considering the multiple stops, the days at sea are spaced well apart to give you a break in between your on-shore activities. If you still think it is too many sea days, take a train.
3) Airfare may get expensive. This cruise will work best for Californians and people within the driving distance of San Diego. Otherwise, you will have to purchase two separate one way tickets. I don't see how you can create a round-trip itenerary to get you from wherever you are to Buenos Aires and then back from San Diego.
4) Taxes are extra. Just like the airfare, you have to price it into your total cost.
5) Tipping is extra. I don't know exactly how the staff gets paid, but your tips are most likely a huge portion of their income. Draw your own conclusions.
6) You need to make bill payment and mail hold/pickup arrangements. With online BillPay services, it may not be that hard.
7) You may be well-advised to purchase a calling card that would work from most places where the ship stops. This way, you staying in touch with family/business partners will only costs pennies per minute. Expect ship-to-shore calls from your cell phone to cost in the $5/min range.
8) Internet access from the ship may be slow and expensive. Plan to be out of touch on sea days and use Internet cafes during stops. When using public Internet terminals, stay away from banking- and finance-related sites that require a login. You never know who is snooping.
9) If you are not retired, have kids, have a daily job, are a full-time student or can't run your business remotely, this is not for you.
10) KILLER DEAL: If you can rent out your place for a month to a short-term visitor, your trip will be essentially free or near free.
11) Although most of the food is free, there are items for which you have to pay. These include all kinds of alcohol (beer, wine, hard liquor), bottled water, sodas and juices. (Non-bottled) water is free, hot tea and coffee is free, iced tea is most likely free. Some kind of juice may be available for free in the morning and/or through room service.
11a) Most likely, you can bring a reasonable amount of alcohol on board with you at the initial boarding. Since the departure port is in a foreign country and requires a flight to get too, it may be a moot point.
12) There is always a food outlet that is open 24-hour a day. However, menu may be limited. If you have a special-diet need, you should check with the cruiseline before booking.
13) Children's services (babysitting and entertainment) may be limited due to the nature of the cruises (repositioning, where families with children are usually few). Expect to meet a lot older folks (above 60). (I am hoping this will not be perceived as age-discriminating - I am just stating a fact).
14) Carton milk (whole, skim and chocolate) for children can usually be obtained at any buffet just by asking. It is freely available in the morning, but has to be asked for the rest of the day. Cereals are available the same way.
