Okay, Beta's finished so I'll post some thoughts.
PvE and "Events"? Utterly brilliant.
First, you have to understand that the game actively scales your character level down to whichever area you're in. While this sounds incredibly bad, in practise it's brilliant. I'll explain further later.
Secondly, the hype about seamlessly joining events? All true. The PvE in this actively encourages team play. I mean, saying it like that really doesn't do it justice. Events ping up an announcement if you're near one, then you just check your map or radar and head for the action. Depending on how much you contribute to an encounter, you'll get a reward accordingly. As long as you're actively participating for more than a couple of kills, it's easy to get the top reward for any encounter. I'm not saying that encounters themselves are easy, just that participating is.
Even if you and your fellow players fail an event, you'll still get a reward when it fails, plus you may unlock an even more interesting and rewarding event. My best experience of the whole weekend was when the Underworld had been allowed to encroach a little too far in to the swamp. Demons and portals were getting out of control over a wide area. Pushing them back to where they started,
a huge boss spawned; this was obviously one of the major encounters they've been touting. Upon defeating him, he dropped a massive boss chest, the only one I saw all weekend, that dished out lots of nice loot to the participants. I'd dealt with the portals and demons prior to this yet had never had the boss spawn; I'm sure he only occurred because the demons had been allowed to spread so far in the first place.
So why is level scaling in this a good thing?
Basically, it means that no matter where you're playing, you can continue to level. This is great for guilds, as it makes helping lower level guild members through early content less of a chore. They need to tweak the rewards somewhat, as while you get the same experience points while fighting in a lower level area or one more suited to your level, lower level areas don't reward higher level players with the same loot that other areas would. I think the best solution here would be to flatten the Karma reward system.
Karma's a resource you get for completing quests and events, which can be used on its own to buy gear from particular vendors. These Karma vendors are the natural evolution of those guys from the original game that would give you equipment in exchange for items dropped by monsters (such as mossy mandibles). The beauty of this new system is that you now have a unified resource for these vendors, so getting gear appropriate to the area you're questing in just requires playing some events or doing some quests. Because they've left in a scale for the karma system, it basically means that higher level players will quickly realise they're better off playing higher level areas, as while they'll get 50 karma for completing an event in a lower level area, they'll get 1,000 or more for doing the same amount of work in a higher level area. Flattening the karma reward system and the cost of items associated with it would alleviate this issue.
Having played Age of Conan recently, I can see that the GW2 team grabbed some inspiration from there.
The world is organised pretty much identically; the map is divided into areas and each area is a massive instance. Think of 2-3 areas from the original game merged together to create one. This division of instances doesn't really cause any issues, as each is absolutely massive, again much like Conan.
Getting around the world is pretty simple, and the skill of ArenaNet's level designers becomes apparent very quickly. You know those times in an MMO where you were forced to take a 30 minute diversion to get to a place on the map that looks like it's only a few feet away? Even with jumping, climbing and mounts? Yeah, those experiences pretty much don't exist in GW2.
On top of that, the've implemented a waypoint system that emulates the freedom of movement around the world from the original game very nicely. As you explore a map, you'll reveal waypoints. At any time, you can open your map and teleport to any waypoint in the world that you've previously discovered. There's a gold cost associated with doing so however. I'm still trying to work out if attaching a cost to such a system is a good idea. Sure, prices are pretty damn trivial; killing a couple of monsters will get you enough copper to teleport to any of the waypoints you've discovered in your current instance. But it could end up becoming prohibitively expensive at higher levels.
One thing I hate about the game is that they've implemented a gear damage system, something I absolutely detest in every other game it appears in. This is one of the components of their death penalty system. If you've been following the game at all, more than likely you're aware of the whole "Downed" system (which, I might add, is utterly brilliant). If not, I'll explain.
When you reach 0 HP in Guild Wars 2, you enter a "Downed" state, where your character lies on the floor but has a few unique skills available to them. For the Warrior these consisted of throwing rocks, throwing something bigger that knocks an enemy down, an instant revival that counts down a timer at the end of which you enter "Defeated" state (ie, die), and a health regen skill. Any other player can choose to revive you, and it's in their interest to do so, as they get experience for doing it. If you then lose all of your health while in the downed state, you become "Defeated", where you can either wait for someone to revive you or teleport to the nearest waypoint. Every time you enter a "Defeated" state, a piece of armour gets damaged, reducing its effectiveness. If the same piece of armour gets damaged twice, it completely breaks, providing you with no benefit at all. The problems with this system?
Firstly, repairs cost money. A trivial amount, but still annoying.
Secondly, unless you're able to obtain the ridiculously rare repair kits, repairs can only be done by certain vendors. Unfortunately there are only 2-3 of these particular vendors per area, inevitably being miles away from where you died, meaning that if you want to remain effective you have to go out of your way to get repairs, lengthening the time it'll take you to get back in to the fight.
I can somewhat understand ArenaNet attaching a cost to armour repairs; they need money sinks all over the place to help regulate the economy, so I think the best solution here would be to add an armour repair vendor close to every waypoint, or do away with them altogether and make repair kits widely available.
Overall though, utterly brilliant, and yes, a much needed evolution of the MMO. And ye gods does it feel good to finally be free of the "Holy Trinity".