Generally taking a casual-medium intensity approach, my experience has been that you have to fight against the efficiency incentive structure in the game to have any fun. Assuming these rules are like prior servers I'd say be very purposeful about how you play.
Up to the level cap you can definitely group and go at whatever pace (at least up through PoP). But pickup groups congregate in a few zones starting around level 12 (unrest-lower guk-seb-velks-grieg's-fire), which is possible thanks to pick zones. It is very possible to level in just a few zones and can be hard to get people to leave them.
One of the side effects of the AoCs and the way they've buffed raid targets is that at max level the most effective way to get good loot is to join a guild doing 72 (later 54) man raids. These are boring and generally trivial, at least for rank and file members. They've been especially boring when I've only really had the playtime to make 1-2 raids a week and so I haven't known the guild well enough to make shooting the shit with people on these big raids any fun. Doing group or lower tier raid content just feels like a waste of time when the big targets are sitting there waiting for you to make an instance with your 71 closest friends.