Here's the official hype copypasta, if you haven't already seen it:
Some features we can look forward to at launch:
>realm vs realm PvP
>no factions FFA
>guild vs guild PvP
>large field PvPvE
>true action combat
>amazing graphics/art style
>clean and fully customizable UI
About the endgame:
The PvP crowd has: open world, bounty hunting, realm vs realm, guild vs guild, and battlegrounds.
As for the PvE crowd, there are 7 confirmed endgame instances as of right now. All have a [Normal] and [Hard] option. These are: Labyrinth of Horror, Black Tower, Kelsaik's Nest, Training Ground, Bibish's Lab, Jabalman's Dome, and Gladusshi's Watch
http://youtu.be/YNrpJvm3bVg | http://youtu.be/PZRdgKmybhE
http://youtu.be/Uh8xMM9LX6A | http://youtu.be/kwxfXm1VukA
>Gamescom 2011 trailer
>TERA E3 2011 trailer
Aside from that, arguably my favorite part of the entire game is the chronoscrolls. It's like EVE online's pilot license extensions, except they are only tradeable once (no marketeer hording), they ONLY add +subscription time (not like EVE, where those licenses add a ton of extra stuff now, making them more like cash shop points), and they drop off of all elite mobs, which, if you are good at the game, you can solo anything. Each scroll is +15 days to your subscription, so if you play a good amount you will only need to pay the first sub fee and then never again. Actually, if you get into a good guild, you won't even need to grind the elite mobs, as long as you contribute I bet they will give the high ranking members the scrolls for free.
Countdown for QoA2 is 10 days. If you don't already know, QoA2 is the first real game expansion for the US version; it adds Battlegrounds, 3 new instances, a new item tier, revamps for almost all classes, and new glyphs, as well as revamp on the pomegranatety Nexus system where you can now form a raid of 10 players and fight one, instead of having to go in a huge laggy mob and only on the weekends.