MMORPG.com has published a preview of the STO character customization system:
Star Trek Online : Inside Beta: Character Customization - Star Trek Online for PC at MMORPG.COM
Classes/Archetype you can choose are:
Tactical Officer (Sounds like the fighting type)
Science Officer (Sounds like the controller type)
Engineer Officer (Defender/Support)
Races you can choose are Human, Andorian, Bajoran, Bolian, Vulcan, and Ferengi and you can also make your custom race with its own traits!
Then there is lots of looks customization including how the uniform looks and such and then you can enter your name and a bio