It's about as realistic as i think we're gonna get in a game to be honest.
The standard wind stuff is in it and as another commenter pointed out it can take some getting used to, but if you know basic sailing you can easily overcome it.

A lot of people seem to forget things like tides, rips and currents when asking these questions and i've never seen that in any game unfortunately. That's the kinda stuff i'd personally like to see, on top of the standard of wind that is. A whole lot more to sailing than just the wind.