Video of some of the bg pvp (structured pvp) in action with the mesmer class(start at 22 minutes): http://www.youtube.com/watch?v=OYXpLDcfkdY
Here are the main features of the game, with probably my favorite feature, the world PvP:
No subscription fees
No subscription fees. 'Nuff said.There is a cash shop but ArenaNet has stated multiple times that they will never, ever, ever offer items that could possibly cause one player to be stronger than another player in PvP. You can still keep your wow subscription while playing GW2 (which is what I'll be doing)
World PvP will also be server vs. server vs. server, Player limits are not yet finalized, but current estimates are that each map will support up to 500 players, split across the three servers, for a total upper limit of 2,000 players across the entire WvW match.
WvW will be accessible to characters immediately after the tutorial instance and players joining WvW will have their level and attributes dynamically adjusted to level 80.
Players may leave or join WvW at any time with only a few restrictions:
Players who have recently changed their home server are restricted from entering WvW for a limited time.
Players who are idle for a certain amount of time will be automatically removed from WvW, but can rejoin at any time.
Players who attempt to join a map that is full can decide whether to queue for a space, or join one of the other maps instead.
Each WvW match takes place across four very large maps containing four different types of objectives. Every 5 minutes, the objectives controlled by each server are totaled and added to that server's cumulative war score.The aim of WvW is to achieve a higher war score than the opposing servers by the end of the two-week battle.
Whenever a tower, a keep or Stonemist Castle is captured by a server, the guild that had the most participating members will have the option of claiming the keep. The claimed keep will then display the banner of that guild, and any WvW upgrades purchased by that guild will apply to nearby allies.
Competitive PvP. Gives you max level, all abilities unlocked, and a set of starter PvP gear. As you play you gain glory to spend on new PvP gear. The gear does not have better stats (so everyone relies on skill) but it will look better and give you more choice as you progress. Also as you gain more glory, the matchmaking system for PvP will place you in matches with players with similar experience. Besides matchmaking you can also join (and possibly create your own) PvP matches via hotjoinable server (think battlefield 3). This lets Guilds and groups of friends play against one another in servers of their own. Also ArenaNet, being the PvP-focused developer they are, will host monthly tournaments consisting of 5v5 single-elimination matches.
Holy Trinity (tank heals and dps)
No Holy Trinity. There are no longer Tanks, Healers, and DPS. Everyone is capable of creating a character that can take some damage, heal some allies, and dish damage out. Everyone has a self-heal skill that they must use to help keep themselves alive, and a dodge skill that evades attacks via the physics engine. You can specialize and create a character that is better at taking damage, healing, or dealing damage, but nobody is capable of just standing and taking massive hits or just standing and healing continuously. If you stand and just try to deal damage without dodging/healing, you will die. Fast. Basically you need to help yourself and help others whenever possible. Everyone can ressurect the dead (even in combat).
Dynamic combat. You can move while casting. You can dodge attacks. The game uses a physics engine similar to Skyrim's, meaning you can actually use abilities while you aren't targeting anything, but if someone runs into that spell/arrow/your hammer then they will be hit. There is still targeting to guide spells and arrows and stuff, but it isn't always necessary.