I don't think it's too different. It does quite a lot of things different from conventional MMO's but it's not some completely alien game. It still looks like an MMO and it borrows heavily from other genres, especially online shooters. If someone has played a game of the following genres, they'll understand Guild Wars 2. (MMORPG, Class Based Shooter-and all shooters are class based nowadays-, Action RPG, Western RPG).