guild wars tends to have different play themes in each campain.
Prophieces was grt for starters, u started low lvled and stayed low until the end, for the most part u were still lving throughout the story, at the last 10 or so missions u finally got to lvl 20.
In factions the game expects u to do all the quests because u r expected to be at lvl 20 by the 4th or 5th mission. The game gets harder by throwing larger mobs of enemies at u.
Nightfall introduced Heros which r AI controled players that u equip, give skills and weapons to, they lvl up with u and gain XP from quests like u, they also can be commanded to use specific skills/not use skills and can be stationed at an area. I found the heros to be much better then the healer henchmen who used ineffective builds. the game itself, much like factions, made u max out to 20 by the 6th or 7th mission.
Eye of the North isn't its own campain, instead, u have to travel to it, its technically in Prophicies map but there is no way to get to it. u get heros again, but these heros r lvl 20 with maxed armor and weapons, so u can go to EotN, get the lvl 20 heros, then go back to prophecies and destroy everything.
My biggest complaint is the PvP for low lvled areas from lvls 1-10, what happened was that some players bought runs to lvl 20 areas, bought the lvl 20 armor and weapons, then pvped with amazing skills and equipment. i did this and litterally took down 4 lvl 8 guys when i was lvl 5. the players just hit 0s on me while i killed them in 3 hits. as a result of everyone doing this, low lvl pvp became normal pvp, except u have to spend massive amounts of money. so low lvl pvp died.