My better half is very prone to motion sickness, and hates even a 20-minute car ferry we often do, where she has to get out of the car to stare fixedly at the horizon, to pretend she's not on a boat.
But she loves the QM2.
We've now done a QM2 transatlantic three times (with the 4th time coming soon), and always in Princess Grill, so always on up on Deck 10, though we're trying Deck 11 next time.
The first time we did a transatlantic, we came loaded with dramamine, prescription scopolamine patches, those little wristbands with the pressure points...
Didn't need any of it.
I'll admit we've had some blissfully smooth crossings, but on any trip of that distance, you'll typically have a mix of weather conditions anyway. But QM2 handles the North Atlantic incredibly well.
One of our crossings was NY - Hamburg, and on that trip, the North Sea was the worst part. We remember standing on our balcony looking at a container ship off the starboard side, watching it crashing up and down, huge waves smashing over the bow... then looking down at our glasses of wine sitting on the table, with barely a ripple.
Should you bring precautionary meds? Sure. We still bring them, we just don't expect to use them.