What's the motion like?
The quick answer is very, very different. At sea, a monohull's roll, heel are familiar-not enjoyable, just familiar. A cruising cat serves up an alternative array of motions: up, down, sideways, forward, aft.
In almost all conditions, the catamarans moves are quick, but they're small in amplitude.
Sailing upwind in windy, choppy stuff, is a kind of quick thrusting.
But thanks to hull sections that are gently rounded, a cat doesn't pound. As far as heel, you'll get 4 degrees: In 12 knots, in 20 knots, in 30 knots of wind, you'll heel 4 degrees.
This is something that's very easy to get used to. Downwind, life is good: A cat absolutely doesn't roll, and the two widely separated, relatively narrow hulls minimize yawing; unlike the corkscrewing of single-hulled boats, cats exhibit superior directional stability. Monohull sailors are inevitably disappointed with a cruising cat's lack of "feel" on the helm, but two hulls do make the autopilot's job a lot easier.
I recommend the Catamaran to anyone who has not ever sailed one. Check it out if you get a chance and see for yourself.