If you purchase Factions, you will be able to travel to the new land, Cantha, with your Ascended characters from Guild Wars (original Prophecies campaign). Inventory items, skills, and other possessions and attainments from Guild Wars remain yours and remain useable within Guild Wars Factions.

What is the new PvP area?
The majority of PvP encounters take place on a new continent: Battle Isles. All players from Guild Wars and Guild Wars Factions will engage in combat on the Battle Isles, although two lower-level PvP areas – the Ascalon Arena and the Shiverpeak Arena – will remain in Tyria and will be accessible on that continent rather than on Battle Isles.

If I do not purchase Guild Wars Factions, will I be able to create Assassins or Ritualists either as primary or secondary professions?
No. Assassins and Ritualists are exclusive to Guild Wars Factions and will not be accessible to players who have purchased only Guild Wars.

Will I be able to team up with the Assassin and/ or the Ritualist players if I don't buy Factions?
While you will not be able to create an Assassin or Ritualist unless you purchase Guild Wars Gold Factions, you will, of course, be able to interact with those who own Guild Wars Factions when you join cooperative ventures or competsitive matches.