Unfortunately, due to my line of work I have had to telework on 2 different 4 day Disney cruises. Both times, I bought the maximum number of minutes. On the first one, I used all of the minutes, on the second one I didn't. I thought the connection speed on the second cruise was MUCH slower.
We are preparing to go in a few weeks... In preparation, I decided to call Verizon and ask them about switching my mifi to an international plan. Verizon looked up the ship and said that it has a 3G cell tower on it, and the mifi will send signal through the cell tower and not through the satellite, which is how the ship internet is sent. The Verizon person said the mifi would be faster than the satellite. (I have no idea if this is true - they weren't trying to "sell" me - I was asking a pointed question.)
For the mifi, it is $25 for 100 mb of data, regardless of time. I thought this was interesting, because with the satellite plan on the ship I remember buying minutes and not data. With the mifi, once you use 100 mb, it automatically renews for another $25 and so on.
When we went on the 4 day cruises, I remembered spending around $100 for the max internet package. With the mifi, I asked Verizon to tell me what my use was, and they estimated that over 7 days I would need 300 - 400 mb of data, which is around $75 - $100. That's fine - I don't mind paying even more than that if the dang thing was FASTER than the satellite. I use a web interface for my work, so the waiting was killing me.
Anyway - I can report later how it went. My 'plan" is to try to get as much done as possible on day 1 and then work on alternating days.
Hope this helps!