A Few More Details:

For the Factions Preview Event, your newly-created characters will begin at Level 20.

You will start out with 20 skills and will then speak to an NPC to select a secondary profession.

Selecting a secondary profession will gain you an additional 20 skills.

Your guild must choose a faction—Luxon or Kurzick.

You can play four higher-level missions—two story missions and two competitive missions—appropriate for your Level-20 characters.

You will be able to experience 15 quest areas.

For all Factions roleplaying characters, certain game elements will be inaccessible. These include: guild halls, the Xunlai (storage) Agents, and Battles Isles. Ship travel to and from Cantha will also be disabled during the event. These game elements are locked down to help assure that unfinished or unbalanced items acquired during the event do not impact the game economy in the long term.

Challenge missions and elite missions will not be available during the FPE.

Item and skill unlocks earned by both your roleplaying and PvP characters during the FPE will remain on your account.

After the event, all Factions roleplaying character inventories and levels will be reset in preparation for the launch of Factions. http://www.guildwars.com/events/ingame/factionspreview.php