how does this compare with WoW, I know its a different genre but my interest is peaked somewhat
Having played quite a bit in Battlegrounds in WoW (L19 Gnome Mage with 2.5k worth of kit/enchants - probably not much, these days), and now in World-vs-World in GW2, I can honestly say I prefer GW2.
Basically, there are four large maps which are all linked, and you are thrown in with players from two other servers. You can choose which map to load into, but can swap between at any time - each server has what can be considered the entrance-map for that server (although you can jump into any map), plus one central map with a massive castle in the centre.
Scattered around each of the maps are various camps, towers, keeps, and that single castle in the central map. Taking control of one of these involves gaining entry (camps are open, all others have one or more gates you need to smash down), then finding and killing the Lord of the location, then keeping players on your side within the ownership circle for a certain amount of time (the more players, the quicker the take-over).
Every five minutes, the scores are updated depending on how many control points your server has control of - 5 points for a camp, 10 points for a tower, 25 points for a keep, and 50 points for the castle. There are 24 camps and towers across the four maps, along with 12 keeps, and the single castle.
Within each location, there is a supply-level, which players can pick up up to 10 supplies, which can then be used to repair damage to a structure, build new structures (siege weapons/defences from blueprints you buy from vendors), or take them with them to build offensive siege weaponry to attack other enemy structures.
Currently, while ArenaNet work out which servers are closely matched, the maps reset every 24 hours, and your server will get matched up against another 2 servers - once things settle down, that reset-time will become a week or two (can't remember which) and you'll remain matched up against the same servers (unless one becomes massively imbalanced), leading to lots of skirmishes against two other servers to try to keep your server's points higher than the other two...