So in a nutshell (for those asking), SWTOR is a cross between WoW and Mass Effect (although it is more like other MMO's than WoW). Bioware has built in the '4th MMO pillar' of Story. The whole game is fully voice acted from fed-ex quests (which don't feel very fed-exy) through to story driven Flashpoints and Operations (instanced dungeons).
The story itself is very KOTORy in that it is set 300ish year after KOTOR. From the 20 level I played it wasn't very clichey, but was definitely star wars.
There are 8 base classes, 4 republic and 4 sith. Each has it's own unique class stroyline and each has 2 advanced classes. Recently in an interview the Bioware CEO's said that if you were to quit your days job to play SWTOR it would take you 10 months to get through every class story once. That doesn't include the flashpoints/ops or group content, PvP or repeatable stuff.
As another indicator of size, BW has said that SWTOR is larger in content size than all other BW games put together.
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