From Thursday to Sunday Fileplanet subscribers have the opportunity to stress test Pirates of the Burning Sea. If you are not a subscriber, you can apply too, but "subscribers get in first" is the rule in this particular case. This being a stress test, server performance will most likely be worse than in the real game. But you should be able to play enough of it to form yourself an opinion on whether you like the gameplay. I'm most interested in the player-run economy, but I guess I won't see much of that in a 4-day test.
And yeah, I know I link to Fileplanet a lot. No, I'm not getting any money from them, just the opposite, it's me who is paying them for a subscription. I know some of you don't like the idea of having to pay for demos or betas. But I'm a sucker for buying games that look interesting. If Fileplanet gives me the opportunity to try before I buy, it takes just two games I decide against to pay for more than 1 year of Fileplanet subscription. So I usually come out ahead. For normal demos it's usually just convenience, I could get the same for free but slower. But MMORPG betas are quite often Fileplanet exclusives. Really worth it for a MMORPG fan and blogger.