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So, there's no auto-attack.
From what I gather the combat mechanic looks like this:
You have to hit a button for each sword swing(Warrior case) or any other skill.
There's no GW2 like "auto-cast" your most basic skill (essentially making it auto-attack with a skill)
There's a 1.5sec GCD on every attack, so if you want to optimize your DPS you must begin intensely mashing a button at about 1.4sec mark so that your next attack comes in at exact time when your GCD is up, as opposed to say 1.6sec after your last action - otherwise you're wasting DPS.
Anyone who played it at PAX or similar, care to comment ?