Healthy, balanced open-PvP is a very difficult thing to both encourage and manage.
I'm a huge fan of the battlegrounds/scenarios form of PvP where some degree of balance can be established in terms of player numbers leaving victory to the side with the best players and most skill. This is exactly how sports are played, from tennis to football matches.
For PvP to be a genuine test of player skill instead of descending into bullying, victimisation, etc rules have to be implemented.
From what I hear on these forums, many people hate battlegrounds/scenarios as a PvP option. I find this strange when this is typically the only option in online FPS games, such as CoD4, which are so popular and litter the X-Fire top 10. They also seem to be the first choice for PvP in games like WAR, which I play atm. Many players moan "There's no RvR!" but why would you want to run around looking for a fight when you can have your battles all set-up and balanced for you? Some people wish Scenarios were taken out of the game. I think they should be made bigger, increased in number and have the RvR removed from the game as a waste of resources. Just put keeps in Scenarios.
Many vocal players seem to like the idea of being able to gank others and thats fine with me, if thats what you enjoy. But I think these players are a minority who are over represented on certain forums and any game that caters to them as a priority will have limited popularity.
Take WoW; not a game I'm a huge fan of but it certainly has a winning forumla. That formula allows ganking on certain realms but also allows you to avoid it on others without totally crippling your PvP options.
I'm currently looking forward to Darkfall. Despite WAR being a blast, there is little feeling of reward for your conquests and the game does feel like it should have been released shortly after WoW in terms of it's overall look and feel. However, I love the basic structure. Darkfall seems to offer everything WAR lacks - graphics, huge range of options, FPS format, no levels, no classes, etc - except in lacks structure. Now this is great if you have piles of time on your hands, but like many people I don't so I won't be able to form or even join fancy 24/7 guilds, wait 30mins for guildies to turn-up then roll out and do something. Nor do I enjoy the type of vacant PvP the game seems to encourage, where prolific ganking just turns these games into hotbeds for the development of the psychotically disturbed adults of the future.