I just re-subscribed and rolled a new character. I'm glad I did, and wanted to share my own (very brief) but impactful experience.
My first character I tried was the Jedi Consular (Sage). I really struggled with the quests on the first planet, Tython. I won't rag on why, as it's purely my opinion, but it just wasn't interesting me.
Folks recommended that I try another class, but I was stubborn and said I'd continue this one. I got as far as Coruscant (not very far, I know) before giving up in frustration about the feel of the class and the quests.
Well, just last night I did try a new character after coming back to the game--a Jedi Knight. I didn't think there'd be much difference between that and the Consular, especially as they both start on the same planet. I was wrong.
I was immediately enthralled by the Knight class quests. I felt like I was at the center of the action and story, plus I enjoyed the melee mechanics better than the ranged consular. (I've played a mage for seven years in WoW, so maybe I'm just tired of ranged classes.)
Anyway, the bottom line that I wanted to emphasize for new players who may be frustrated is that first impressions don't always count if you've chosen the wrong class. A ton of work when into making very different stories for each class, and it's well worth trying more than one before giving up.