Guild Wars 2 is big, like really big, and there is an absolute ton to see and do. So much so that I'm going to hold off on a formal review in order to get further into the experience. In the mean time, here's a primer on a few things you should know before diving into the world of Tyria.
Chances are that if you're interested in Guild Wars 2 that you might have played the original Guild Wars, but a lot has changed since 2005. While the original was described by the developers as a competitive online RPG instead of a straight MMO, Guild Wars 2 is much more akin to its massively multiplayer cousins. There are a few mechanics and systems that are new and unique enough to throw even MMO veterans for a loop.
It all starts before you even create your first character. Selecting your home server is a big deal in Guild Wars 2, because you're limited to creating characters on a single server. This minimizes potential issues with World vs World PVP and works in with some of the game's microtransaction monetization that replaces monthly subscriptions. Currently though, server transfers are free and without time restrictions, so if you accidentally roll on a server away from your friends it's an easy fix. In the future there will also be a handy guest feature that will allow players to temporarily join other servers as long as they have a friend there.
Once you've settled on a home server, then you can start making your character. In Guild Wars 2 these can consist of any combination of the 5 races and 8 professions available, but there is no inherent benefit or penalty associated with certain configurations. An asura warrior is just as good as a norn, despite the size difference. Each race does have a few flavorful racial skills, but your character race is primarily going to affect your appearance, starting area and personal story. Your character's personal story is why you get asked a series of questions after customizing your character. These range from background questions like if you're orphaned peasant or noble born, but also what your goal or greatest regret is. Your answers will shape your story quests, though they ultimately all lead towards the overarching plot of Guild Wars 2's story.
All of the professions share the same four primary attributes: power, precision, toughness and vitality. Power makes you hit hard, be it a fireball or an axe to the face, while precision increases your chance to score a critical hit. Toughness increases your armor, and vitality increases your health. There are also secondary attributes for statistics like healing power and how long your conditions last. Now it might be tempting to stack everything in a single stat in order to specialize, but Guild Wars 2 gets rid of much of the tank, healing and damage holy trinity. Healing power might not seem like an important stat for a thief, until you consider you're primarily going to be healing yourself rather than relying on someone else.
One of the first messages you're likely to see when you enter the world, especially during this busy launch period, is a notification of being placed into overflow. Instead of running queues where you simply wait your turn in line if the server is at capacity, you are instead put into an overflow shard and the queue happens behind the scenes while you play. These overflows function just like your regular server that you can play, level up and adventure on, and you'll have all your normal access to your bank, trading post and what not. Once space opens up, you'll receive a notification to travel there or you can put yourself back in queue if you're in the middle of an event.