Ok.
Been playing for around 2hrs total now as an Imperial agent.
Observations.
Graphic-wise, it's much smoother than WoW, but does not seem as colourful as WoW is.
Interactions: These are cool, in a limited way so if you have ever played either KOTOR's, it will be *very* familiar, to the point that if you don't see anyone else playing, you could quite easily feel you are just playing another KOTOR.
Storyline/quests: On a par with WoW, go here, kill this or collect that, pretty standard for a free roaming game.
For Free, it's worth a whirl if you are a fan of the SW-verse, for Pay to play, I dunno. Most people pay for "end-game" content (which you don't get in the free version) or PvP battlegrounds which I have read pretty colflicting reports on (too much stun/crowd control mainly).
I say if you like SW, give it a run, you have nothing to loose.