There is no question that catamarans are faster under power or sail. Whatever your cruising goals are, catamarans will usually move you about more quickly than a monohull.
Catamarans have shallow drafts. This means catamarans can get into places monohulls yachts often cannot reach, and that they can also anchor closer to shore.
However, more and more charter cats now have small "sacrificial" keels to improve close-hauled performance.
Lastly, I personally enjoy the phenomenal maneuverability of the cats. With 2 engines spread apart, you can pivot a cat of any size literally around the boat's central axis – and without the help of the rudders. The autopilot works particularly well on cats, on a tracking standpoint.