Think of a medieval tournament.
You probably thought of jousting, didn't you? This is the modern audience's romanticized view of medieval tournaments: two heavily-armored knights on horseback, charging at each other, lances in their hands. The winner takes on someone tougher in the same contest. Repeat until only one knight remains. But for most of the 300 or so years that tournaments happened in Europe, the joust was among the least important events. There were other events: contests of swordsmanship, horsemanship, and archery among them. But the main event of the tournament was actually the French-originated mêlée, simplified to the English word melee.
In the melee, dozens or hundreds of knights would be divided into two teams and they would simulate a full battle, often taking all day! This was a hugely popular event. It would open with both sides charging at each other on horseback with lances (the origin of jousting). Those that remained on horseback continued fighting that way until knocked or dragged from their saddles. Those unhorsed would fight on foot until they were injured, exhausted, or killed. The melee would continue until one side or the other was victorious, or until the sun went down. Though it was a "game", the tournament melee was often soon indistinguishable from a real battle, with knights from rival kingdoms taking advantage of real-life rivalries or attacking real-life enemies. Often, knights were captured in the melee and held for ransom -- it was considered among the valid rewards for the victors of the melee.
And ambushes and accidents happened. It was not at all uncommon for a knight on team A to be focused on attacking a knight on team B in front of him, tiring but close to victory, only to be brained from behind by a second knight on team B with a mace. Serious injury or death would be the result, and it wasn't always unintentional.(1) Ganging up was also common. A lord might enter the tourney field with his tenant knights around him, protecting him from harm so that he could come through the entire melee as the victor, not unlike what happens today in competitive cycling.
Black Prophecy PvP is a lot like medieval tournament melees.
At the end of a long string of required PvE missions, where you are introduced to the game mechanics, your ship, the story, the players, the crafting system, and everything else about the game, you are finally required to "choose a side." The two sides are the Tyi, a human race off-shoot that has chosen to augment themselves with technology (think cyborgs) and the Genides, a second off-shoot focused on biological enhancements (think splicers from Bioshock).
At the lower level of play, it doesn't seem to matter very much which side you choose. Your ship stats don't even change very much; the previous upgrades that you've bought or crafted for your previous non-Tyi/non-Genide ship are just transferred over with no changes. This might or might not change at higher levels of play. The U.S. beta of Black Prophecy doesn't really work well past level 12 or so, so I can't say.
Once you choose a side, though, you are transferred from the starting all-PvE areas to a new set of mixed PvE/PvP areas. And when I say mixed, I mean truly mixed. If you accept a PvE mission, you'll be going into a PvP area to complete that mission. Others in that area might be completing PvE missions, or they might be there specifically to hunt people trying to complete PvE missions. They might be on your side, or they might be on the other side. They might be there to hunt the hunters. And maybe they have three or four of their friends logged in to help them. Or just maybe they're in the area just to test a new ship fitting by shooting a few rats. Or a few other players. The guy attacking you might be level 6 and be unable to penetrate your shields, much less your armor. Or maybe he's level 12, with a plasma-based weapon that can kill you in five or six shots. People on your side might jump in to defend you if you get attacked, or they might take the opportunity while you're keeping the hunters busy to complete a PvE mission themselves instead.
"Chaotic" doesn't even begin to describe it. ;-)
It's definitely not how I would have designed things. In a way, it reminded me of the old Crimson Skies Xbox game, and is also in some ways similar to Global Agenda PvP. But in both Crimson Skies and GA, you are at least guaranteed an equal number of combatants and similar levels of weaponry. Black Prophecy makes no such promises. There's a huge difference between a level 6 player and a level 12 player in BP. In that way, it's similar to World of Tanks, but again, WoT at least gives you relatively equal teams that will hopefully work together.
But, on the flip-side, Black Prophecy practically enforces socialization. It's a survival technique. If you enter the melee with a half-dozen of your friends around you, you can take control of and dominate one of the zones. Once you're in control of it, you can either PvP to your heart's content against anyone silly enough to enter "your" zone, or you can use that control of the zone to complete PvE missions in relative peace. When your gang breaks up and your control over that zone fades, it returns to its natural chaotic free-for-all state.
So, from that perspective, it's an interesting choice in terms of game design.
But is it the correct choice? I'm not sure yet, but I'm leaning toward "no". The difference in level is the biggest factor for me. The difference between L6 and L12 players in this game really is huge. Maybe if there were three zones for levels 6-9, and three more for 10-12? But the difference in team sizes is also a bigger factor. You don't know until you enter a zone and try to accomplish something in it if that zone is being controlled by your side, the other side, or nobody at all.
(1) George R.R. Martin, author of the A Song Of Ice And Fire series of books, missed a real trick when describing tournaments on Westeros. While he mentions melees in passing, apparently jousting is the popular event there. How much more fun would it have been had he made melees the popular event? A few dozen Lannisters and Starks and Tullys and Baratheons and Freys taking their mutual antagonisms out on each other on a simulated battlefield where "accidents" can happen? Would have been awesome. Big miss there, GRRM.