Same as a monohull. Same as a monohull. Ah, let's hear it for comfort. With more above and below living space, the party is bigger. The unsinkable multihull has a flatter ride and no broaching.
Speed is generally greater but it depends on the model.
Greater stability, smoother rides, more living space, better speed. A trimaran is more like a monohull, but it's wider and more stable. It generally has less interior living space than a larger catamaran. Trimarans are easy to single hand sail and tack because everything is lead to the center cockpit. Under 35' trimarans provide more useable space.