First of all this is the forum for gw, but I'll try and answer it as much as possible.
Both GW and GW2 won't have monthly fee's. as far as GW1 goes, beside the 3 campaigns and the expansion there a few things you can buy extra. mostly they are cosmetic and don't give any ingame advantage. If they give an advantage it is very minor and if you don't get it (like me) you won't feel being left out.
GW1 only have humans and core 6 classes (wich come with any of the three campaigns). those are warrior (melee/tank), Elementarier (caster/nuker), Necromancer (caster/nuker or crowd control), Mesmer (caster/crowd control), Monk (healer) and ranger (bowman).
The 2th campaign called factions comes with two extra ones: Assasin (ninja) and Ritualist (caster/healer/crowd control/buffer). The 3th campaign called nightfall comes with dervish (melee/scythe user/buffer/debuffer) and paragon (spear thrower using shoots to buff and prot).
You can start in any of the three campaigns (but not in the expansion), the assasin and rit can only be started in factions, the dervish and paragon only in nightfall.
lvl-cap in GW is lvl 20 and getting there is considered tutorial. This game is different then most mmorpg's cause the focus is on the skills you bring. you can only bring 8 skills, as you progress through the story you unlock new skills, but you can never fight with more then 8 (to switch you have to go to a town). The game is 8 years old and was made for average pc's then. Graphics are therefore very low but that also makes it very playable on almost every pc or laptop. I've been playing for over 4 years now and I'm still enjoying myself. Keep in mind that besides towns and outposts the game is fully instanced. So no random encounters with other players when you on the field (you can play with others but you have to group up in an outpost or a town.
So for the price you get a lot of game, the three campaigns cost 25 euro (for all three!), and the expansion another 15 euro.
Keep in mind though that at august 28th GW2 will come out. This is a totally new game, with open envirements (so you can meet other players while playing), new classes and a totally new concept. The cost-structure will be the same (though it is a new game so you have to pay bout 60 dollar). You don't need to pay anymore to keep on playing (although I expect they come with expansions, like in gw1). It will be playable on average computers (if you bought a computer the last year your very likely be ok). If you want to know more bout it you might want to start with watching the mmo-manifesto. This described their mission when they created the game. You find it here:
http://www.guildwars2.com/en/media/v...ideo-manifesto.
