In addition to the CD-sized download (which, if you're a 3D/FPS gamer, isn't much, I've had game patches weight in at 800+mb) VSK4 isn't much more of an improvement over VSK3 in regards to features. The graphics capabilities have been ramped up a little bit, but not much. Surfing on waves is MUCH easier than it was in VSK3. If you don't have broadband, then don't bother getting this game, it wont work online. As it is, the netcode is suspect at best. When someone enters or exits the race while you're racing, the game will freeze for a couple seconds. This is particularly fun when you're in the middle of a gybe or a mark rounding as when it unfreezes, you'll be in the rocks, rounded up, or broached.

However, it is still the best sailing simulator/arcade out there.

And yes, there are spinnakers and yes, they do work almost the same way as in real life. (there aren't any capsizes in VSK)