Taking my 9th cruise in a month and will use Bonine as always. My young daughter has taken it as well. It does not have the same side affects as dramamine (sleepiness, dry mouth, spaced-out feeling). It might make you yawn a little, but that's it.
Nothing (including Bonine) works quite as well if you wait until you feel sick to take it. It's best to take a Bonine about 2 hours before the motion starts. You can take up to 2 in a 24 hour period, but I normally only need one a day. I rode out a hurricane on a RCCL (Rhapsody of the Sea) cruise year before last and didn't get sick, like so many others because of the Bonine.
By the way, every cruise line I've been on has free packets of Bonine (but with the pharmaceutical name) for passengers but I always take my own so I don't have to go looking.