I brought the iPad and Laptop on my last trip on the Fantasy...
I bought three of the $150 packages (1500 minutes), but I was able to expense them at work.
I ended up about 200 minutes shy of 1500...but, it worked well. Better in some parts of the ship than others (worked great in midship, for example), but far better than I expected. I was able to connect to all company resources (VPN, remote access, email, secure chat, etc) that I needed.
I wouldn't try and stream videos over it (though I did fiddle on YouTube a bit and it worked ok), and I did have issues uploading larger files and pictures.
Still, it was very relaxing not to walk into a firestorm from work when the boat got back from the trip, or try and find wifi access in port of calls to catch up.
The reason I bring this up is...there wasn't much delay...so, while "pay per minute" harkens back to the old dial up days, when planning out how many minutes you anticipate using, most services are going to be very responsive. So, it's not going to take you much longer to say, check and send emails, than it does on land. Therefore, if that's all you plan to use it for a few times on your trip...pay by minute!
One thing to note...when you sign in to the internet service from your personal devices, there is a special sign out link you MUST use when you are done with the Internet. It's worth stopping by guest services and picking up one of their instructional handouts if you are unsure about the system.
If you don't, even if you shut off your computer or disconnect from their wifi, your meter will continue to run and you will be charged. Just keep that in mind.
Cheers!