I take my laptop along on cruises so I can post updates here, download e-mail, and do a quick check of a couple other websites.
The connection is never especially fast, although I had a pretty decent speed on the Holiday this past March - I'd say it was in the 256k range. But dropouts are common (you are dealing with a moving ship and satellites). Even by doing things smart - like writing my updates for this forum offline in Word and then doing quick copy/pastes to the message blocks - those minutes still pile up quickly. The cruise lines actually like people who bring their own laptop since you quickly leave their access page and are in your own familiar surroundings (your homepage, etc) and will tend to forget about the time you are using since things will seem like you are at home on your wireless broadband service.