I just love the way this game is. It starts of really easy, first missions are do-able without the slightest tactic so you can actually learn the game. Then you are dropped right into post searing and things get a bit more difficult.
You can still do well though, even on your own if you are careful enough. Then comes the shiverspeaks. No more solo missioning, you need a party and on top of that a party that knows what to do. Not much tactic needed yet, you can just keep on partying in PuG.
When you reach Kryta the Game slowly forces you to actually THINK what you are doing and what your purpose is in the party. Hitting the Desert, no party will survive even the slightest bit without suberb teamwork. And doing the Ascension Missions then you are awfully screwed if you don't learn the meaning of patience and logic.
I just love the way the game makes you learn the essentials of teamwork.
Starting slowly but getting more demanding in the end.
____________
About PvP
I'm going Melee Mesmer (Mesmer/Warrior) and so far it is working out great (as soon as i got illusionary weaponry that is...). I even had warriors run from me, which was a fatal mistake as that got them a conjure phantasm

I you're interested in the build i can post it later on.