beldeti

You might be referring to the timeline for Guild Wars: Eye of the North, which does happen some years (8 to 10 years) after the events in Prophecies. That's why you have a young Gwen in Prophecies, and a grown-up Gwen in Eye of the North.

You mentioned a trailer, you may have seen the GW:EN trailer -- I don't know of any trailer for GW2 yet.

To the OP: Qbert24 has raised some interesting points, moreso that he's had experience in both WOW and GW so you can draw comparisons more easily from his post.

Like Qbert24 suggests, you can try out Guild Wars: Prophecies first -- as it's the oldest, a little hunting around and you can buy an account for cheap.

Fileplanet is currently running a trial key giveaway, but you need to subscribe to them first.. Not sure if there are other ways to get trial keys. I'll see if I can still scrounge up unused trial keys at home.

Ethelwulf

GW focuses a lot in PvP. And please, don't join if you're the kind of gamer that looks to be high level and show your uberness, you won't find that in here, not at all.
The main objetive of GW is PvP, and besides that, story completion. That means, it doesn't matters wether you're high level or not, no one cares