Some guys belonging to the Coldfront crew managed to score a spot in the closed beta of Pirates of the Burning Sea. They've written up a bit of a preview/review of the beta experience that they had.
Overall, it looks like the game is shaping up greatly. It's beautiful even on the mid-low-end system that one of the testers was using. Of course, there's still a few bugs that they are weeding out of the game, but it seems the game play is all there and totally original. Vessels are strongly influenced by the wind, so much so that it can decide the outcome of battles. Weapons and ammo types are numerous and usage of each varies, but ammunition is also effected by wind. Seems accuracy is as important (if not more) as having the biggest ship and the best weapons. Players also have a limited ability to dodge attacks. The game goes on a system of actual attack connection instead of the roll of the dice system that many other games depend on.
Overall, it's looking fantastic!